Java基础知识之StringWriter流的使用

 //字符串缓冲过区
    private StringBuffer buf;

  /**
     *  利用默认大小的StringBuffer创建字符输出流
     */
    public StringWriter() {
        buf = new StringBuffer();
        lock = buf;
    }
 
    /**
     * 使用指定大小的StringBuffer创建字符输出流
     */
    public StringWriter(int initialSize) {
        if (initialSize < 0) {
            throw new IllegalArgumentException("Negative buffer size");
        }
        buf = new StringBuffer(initialSize);
        lock = buf;
    }

write(int c)

  /**
     * 从指定字符数组的下标off开始写len个字节到流中
     */
    public void write(char cbuf[], int off, int len) {
        if ((off < 0) || (off > cbuf.length) || (len < 0) ||
            ((off + len) > cbuf.length) || ((off + len) < 0)) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return;
        }
        buf.append(cbuf, off, len);
    }

 
    /**
     * 写一个字符串到流中
     */
    public void write(String str) {
        buf.append(str);
    }

    /**
     * 写一个字符串的一部分到流中
     */
    public void write(String str, int off, int len)  {
        buf.append(str.substring(off, off + len));
    }

    /**
     * 将缓冲对象的值转成字符串输出
     */
    public String toString() {
        return buf.toString();
    }
 
    /**
     * 返回流的字符缓冲对象StringBuff
     *
     * @return StringBuffer holding the current buffer value.
     */
    public StringBuffer getBuffer() {
        return buf;
    }

    /**
     * 关闭流无效，关闭后调用该类方法不会报异常
     */
    public void close() throws IOException {
    }

public void process_
(Person person, Writer writer); 

Writer writer = ...;
StringWriter out = new StringWriter(writer);
process(person, out);
StringBuffer result = out.getBuffer( ); 

Reader in = new StringReader("<conf><panic level="5"/></conf>");
alarm.loadConfig(in);