db4o 数据库服务端配置参数详解
db4o 是一个开源的对象数据库，它允许开发者以简单的编程方式存储和检索对象。db4o 的服务端配置是确保数据库高效、稳定运行的关键。本文将围绕 db4o 服务端配置参数进行详细解析，帮助开发者更好地理解和使用 db4o 数据库。
1. db4o 简介
db4o 是一个纯Java的对象数据库，它支持对象持久化、事务处理、索引和查询等功能。db4o 的核心优势在于其简单易用的API和高效的性能。它广泛应用于嵌入式系统、移动应用、Web应用等领域。
2. db4o 服务端配置参数详解
db4o 服务端配置参数主要包括以下几个方面：
2.1 数据库文件
- Database File（数据库文件）：指定数据库存储的文件路径。默认情况下，db4o 会将数据库文件存储在当前目录下，文件名为 `data.db4o`。
java
Database db = Database.openFile("path/to/database/file.db4o");
2.2 数据库模式
- ClassFilter（类过滤器）：用于指定哪些类需要被持久化。默认情况下，所有类都会被持久化。
java
db.setClassFilter(new AllClassFilter());
- ObjectFilter（对象过滤器）：用于指定哪些对象需要被持久化。可以通过实现 `ObjectFilter` 接口来自定义过滤逻辑。
java
db.setObjectFilter(new ObjectFilter() {
public boolean accept(Object obj) {
// 自定义过滤逻辑
return true;
}
});
2.3 数据库性能
- Cache Size（缓存大小）：指定数据库缓存的大小。缓存可以显著提高数据库的读取性能。
java
db.setCacheSize(1000); // 设置缓存大小为1000
- Concurrency Level（并发级别）：指定数据库的并发级别。db4o 支持多线程访问，通过设置并发级别可以优化数据库性能。
java
db.setConcurrencyLevel(10); // 设置并发级别为10
- Transaction Log Size（事务日志大小）：指定事务日志的大小。事务日志用于记录数据库的更改，以便在系统崩溃后进行恢复。
java
db.setTransactionLogSize(1000000); // 设置事务日志大小为1000000
2.4 数据库安全
- Password（密码）：设置数据库访问密码，确保数据库的安全性。
```java
db.setObjectClassAuthorization(new AllAllowed());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
db.setObjectClassPermissions(new AllAccess());
db.setObjectPermissions(new AllAccess());
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