钩入System.out.println();并修改 [英] Hook into System.out.println(); and modify

问题描述

我想修改System.out.println();打印的输出.这怎么可能? 可能-我已经在Bukkit/Craftbukkit中看到了.如果插件正在使用System.out.println(String string)打印字符串； Bukkit将时间/日期和记录状态添加到字符串中. 我想像Bukkit一样.

I would like to modify the output printed by System.out.println();. How is this possible? It is possible - I've seen it in Bukkit/Craftbukkit. If a plugin is printing a string with System.out.println(String string); Bukkit adds a time/date and logging status to the string. I would like to do the same like Bukkit.

推荐答案

您可以更改用作标准输出的PrintStream:

You can change the PrintStream that is used as the standard output:

System.setOut(PrintStream out)

创建自己的 PrintStream 实现，它将所需的任何额外信息打印到(旧)标准输出，并使用以下命令进行设置:

Create your own PrintStream implementation which prints whatever extra info you want to the (old) standard output, and set it with:

System.setOut(myStream);

示例:

以下示例在使用String之前，打印当前时间毫秒. html#println-java.lang.String-"rel =" noreferrer> PrintStream.println(String x) 方法:

The following example prints the current time millis before each printed String that is printed with PrintStream.println(String x) method:

PrintStream myStream = new PrintStream(System.out) {
    @Override
    public void println(String x) {
        super.println(System.currentTimeMillis() + ": " + x);
    }
};
System.setOut(myStream);
System.out.println("Hello World!");

输出:

1420553422337: Hello World!

注意:

此示例仅覆盖 PrintStream.println(String x) 方法，因此调用PrintStream的其他打印方法不会将时间戳添加到输出中.

This example only overrides the PrintStream.println(String x) method, so calling other print methods of PrintStream would not add the time stamp to the output.

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