背景：在SPRING 框架之中， 有一個服務端需要提供多種形態的服務，這里的多種形態只是返回值得展示形式（其實 數據內在邏輯完全一樣）， 比如：
形式1： JSONP({“key1”: value1, "key2":value2, "key3":value3, ....})
形式2： {“key1”: value1, "key2":value2, "key3":value3, ....}
為了使得后台業務處理代碼一樣（不做任何區分），現在理由過濾器，對返回接口進行處理，根據需要加上 ：JSONP(...)
主要實現步驟如下：
1. 在web.xml 中配置過濾器
<filter>
<filter-name>RewriteResponse</filter-name>
<filter-class>com.robin.filter.RewriteResponse</filter-class>
</filter>
<filter-mapping>
<filter-name>RewriteResponse</filter-name>
<servlet-name>/*</servlet-name>
</filter-mapping>
// 斜杠星代表匹配任何請求
2. 重點在於RewriteResponse 過濾器
public class RewriteResponseFilter extends Filter {
public String description() {
// TODO Auto-generated method stub
return null;
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException {
// TODO Auto-generated method stub
ResponseWrapper responseWrapper = new ResponseWrapper((HttpServletResponse) response);
try {
chain.doFilter(request, responseWrapper);
} catch (ServletException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String responseContent = new String(responseWrapper.getDataStream());
RestResponse fullResponse = new RestResponse(205, "OK-MESSAGE",responseContent);
byte[] responseToSend = restResponseBytes(fullResponse);
response.getOutputStream().write(responseToSend);
}
private byte[] restResponseBytes(RestResponse response) throws IOException {
String serialized = new ObjectMapper().writeValueAsString(response);
return serialized.getBytes("UTF-8");
}
}
3. 通用業務類（用於返回）
public class RestResponse implements Serializable {
private int status;
private String message;
private Object data;
public RestResponse(int status, String message, Object data) {
this.status = status;
this.message = message;
this.data = data;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public Object getData() {
return data;
}
public void setData(Object data) {
this.data = data;
}
}
4. 實現ServletOutputStream 指定的擴展
public class FilterServletOutputStream extends ServletOutputStream { DataOutputStream output; public FilterServletOutputStream(OutputStream output) { this.output = new DataOutputStream(output); } @Override public void write(int arg0) throws IOException { output.write(arg0); } @Override public void write(byte[] arg0, int arg1, int arg2) throws IOException { output.write(arg0, arg1, arg2); } @Override public void write(byte[] arg0) throws IOException { output.write(arg0); } }
5. 替換原來的輸出
public class ResponseWrapper extends HttpServletResponseWrapper { ByteArrayOutputStream output; FilterServletOutputStream filterOutput; HttpResponseStatus status = HttpResponseStatus.OK; public ResponseWrapper(HttpServletResponse response) { super(response); output = new ByteArrayOutputStream(); } @Override public ServletOutputStream getOutputStream() throws IOException { if (filterOutput == null) { filterOutput = new FilterServletOutputStream(output); } return filterOutput; } public byte[] getDataStream() { return output.toByteArray(); } }
文章應用: http://stackoverflow.com/questions/25020331/spring-mvc-how-to-modify-json-response-sent-from-controller