import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import java.io.*;
public class ResponseWrapper extends HttpServletResponseWrapper {
private ByteArrayOutputStream bytes = new ByteArrayOutputStream();
private HttpServletResponse response;
private PrintWriter pwrite;
public ResponseWrapper(HttpServletResponse response) {
super(response);
this.response = response;
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
return new MyServletOutputStream(bytes); // 将数据写到 byte 中
}
/**
* 重写父类的 getWriter() 方法,将响应数据缓存在 PrintWriter 中
*/
@Override
public PrintWriter getWriter() throws IOException {
try{
pwrite = new PrintWriter(new OutputStreamWriter(bytes, "utf-8"));
} catch(UnsupportedEncodingException e) {
e.printStackTrace();
}
return pwrite;
}
/**
* 获取缓存在 PrintWriter 中的响应数据
* @return
*/
public byte[] getBytes() {
if(null != pwrite) {
pwrite.close();
return bytes.toByteArray();
}
if(null != bytes) {
try {
bytes.flush();
} catch(IOException e) {
e.printStackTrace();
}
}
return bytes.toByteArray();
}
class MyServletOutputStream extends ServletOutputStream {
private ByteArrayOutputStream ostream ;
public MyServletOutputStream(ByteArrayOutputStream ostream) {
this.ostream = ostream;
}
@Override
public void write(int b) throws IOException {
ostream.write(b); // 将数据写到 stream 中
}
}
}
我想知道这里的private ByteArrayOutputStream bytes = new ByteArrayOutputStream();
bytes并没有进行赋值操作,但是通过debug发现其最终存储了响应的内容,想不明白是在哪进行操作的