FileOutputStream

[chsunnyboy]

为什么一下两段代码效果一样，哪位高手给解释一下

String filename="C://Users//Administrator//Desktop//极速传输//1.script";
File file=new File(filename);
try {
PrintStream printStream = new PrintStream(file);
System.setOut(printStream);
} catch (FileNotFoundException e) {

e.printStackTrace();
}
String filename="C://Users//Administrator//Desktop//极速传输//1.script";
File file=new File(filename);
FileOutputStream fileOutputStream;
try {
fileOutputStream = new FileOutputStream(file);
PrintStream printStream = new PrintStream(fileOutputStream);
System.setOut(printStream);
} catch (FileNotFoundException e) {

e.printStackTrace();
}

[zhjdg]

看源代码就知道。 最终差别就在boolean autoFlush 第一true 第二false

private PrintStream(boolean autoFlush, OutputStream out) {
        super(out);
        this.autoFlush = autoFlush;
        this.charOut = new OutputStreamWriter(this);
        this.textOut = new BufferedWriter(charOut);
    }

[百里马]

    public PrintStream(File file) throws FileNotFoundException {
        this(false, new FileOutputStream(file));
    }

    public PrintStream(OutputStream out) {
        this(out, false);
    }

    public PrintStream(OutputStream out, boolean autoFlush) {
        this(autoFlush, requireNonNull(out, "Null output stream"));
    }

    private PrintStream(boolean autoFlush, OutputStream out) {
        super(out);
        this.autoFlush = autoFlush;
        this.charOut = new OutputStreamWriter(this);
        this.textOut = new BufferedWriter(charOut);
    }

两者确实一样，因为你传file进去，它内部也会创建一个FileOutputStream

[chsunnyboy]

楼上最后的私有方法是什么意思啊 private PrintStream(boolean autoFlush, OutputStream out) { super(out); this.autoFlush = autoFlush; this.charOut = new OutputStreamWriter(this); this.textOut = new BufferedWriter(charOut); }

[百里马]

引用 5 楼 chsunnyboy 的回复:

楼上最后的私有方法是什么意思啊 private PrintStream(boolean autoFlush, OutputStream out) { super(out); this.autoFlush = autoFlush; this.charOut = new OutputStreamWriter(this); this.textOut = new BufferedWriter(charOut); }

这个才是真正的构造方法，被私有化的 对外提供的构造方法，最后都是通过这个方法来初始化的

[KJZL]

效果一样，但实现的方式和效率不一样，一个是用打印流传输文件，一个是用文件输出流传输文件。