java - 如何使用 java FIle i/o 替换、删除或更新文件中的行

Question

以下是我的 java 类文件:

Public class subscriberAction {
private Service1 s1 = ServiceFactory.getServiceImpl1();
private Service2 s2 = ServiceFactory.getServiceImpl2();
----
----
----

public Service1 getServiceImpl1Obj(){
    -----
    ----
    return s1.getInstance();
}

public Service2 getServiceImpl2Obj(){
    -----
    ----
    return s2.getInstance();
}

}//类(class)结束

我想通过动态使用java代码来删除私有(private)类变量并修改返回语句，如下代码所示。如果我运行编程的java文件，SubscriberAction java文件应该像这样修改。

Public class SubscriberAction {

public Service1 getServiceImpl1Obj(){
    -----
    ----
    return ServiceFactory.getServiceImpl1().getInstance();
}

public Service2 getServiceImpl2Obj(){
    -----
    ----
    return ServiceFactory.getServiceImpl2().getInstance();
}

}

你能帮我写一下java代码吗？

Answer 1

您不能直接在您的文件上执行此操作。以下是实现它的方法:

1. Read your original file line by line
2. If there is no modification required for the line, copy it to a backup/temp file
3. If line change is required, write the updated line to the backup/temp file. If line is not required, don't write it to the backup/temp file.
4. Once reading the original and writing to the backup/temp is finished, delete the original file
5. Rename the backup/temp as original file

我希望你能编写同样的代码!