在springmvc+mybatis的项目中，利用mybatis分页插件mybatis-paginator进行分页查询，结果出现了500异常，后端又没有明显的报错。
原来的写法，返回Map对象，由springmvc里面的机制转为json对象,这样就会导致，在转json过程中的报错，都隐藏了，无法抛出，前端获取不到正确的数据，
最后就出现了500的异常。
@RequestMapping(value = "/query")
@ResponseBody
public Map<String, Object> data(HttpServletRequest request, HttpServletResponse response, CreditloanInfoParams params) {
Map<String, Object> data = new HashMap<String, Object>();
if(params==null){
params=new CreditloanInfoParams();
}
PageList<CreditloanInfo> list = (PageList<CreditloanInfo>) creditloanInfoService.getCreditloanInfoListData(params);
data.put("total", list.getPaginator().getTotalCount());
data.put("rows", list);
return data;
}
改成使用fastJson主动转化为json格式的字符串，这样的好处是，转json过程中如果出现错误，会有很明确的提示。
@SuppressWarnings("unchecked")
@RequestMapping(value = "/query")
@ResponseBody
public String data(HttpServletRequest request, HttpServletResponse response, BlackParams params) {
//Map<String, Object> data = new HashMap<String, Object>();
/*PageList<Blacklist> blackDatas = (PageList<Blacklist>) blackService.getPageData(params);
data.put("total", blackDatas.getPaginator().getTotalCount());
data.put("rows", blackDatas);*/
//blackService.getPageData(params);
/* Map data = new HashMap();
PageList<Blacklist> blackDatas = blackService.getBlackListData(params);
data.put("total", blackDatas.getPaginator().getTotalCount());
data.put("rows", blackDatas);*/
return JSON.toJSONString(blackService.getPageData(params));
}
最后发现是转json中出现了空指针异常。修复后，问题解决。
补充知识：springboot 使用过滤器获取response内容保存接口访问日志
一、创建过滤器
1. 在spring boot的启动入口出添加注解 @ServletComponentScan
@SpringBootApplication
@ServletComponentScan
public class Application {
public static void main(String[] args) {
SpringApplication.run(Applicatioin.class, args);
}
}
2.新建过滤器AccessLogFilter.java
@WebFilter(filterName = "accessLog", urlPatterns = "/api/*")
public class AccessLogFilter implements Filter {
@Autowired
AccessLogMapper accessLogMapper;
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
long startTime = System.currentTimeMillis();
ResponseWrapper wrapper = new ResponseWrapper((HttpServletResponse) response);
HttpServletRequest req = (HttpServletRequest) request;
chain.doFilter(request, wrapper);
long endTime = System.currentTimeMillis();
Gson gson = new Gson();
// 获取response返回的内容并重新写入response
String result = wrapper.getResponseData(response.getCharacterEncoding());
response.getOutputStream().write(result.getBytes());
String uri = req.getRequestURI();
AccessLog log = new AccessLog();
log.setMethod(req.getMethod());
log.setUrl(uri);
log.setParameters(gson.toJson(req.getParameterMap()));
log.setResponseCode(String.valueOf(wrapper.getStatus()));
log.setResult(result);
log.setCreateDatetime(new Date());
log.setTimeConsuming((int)(endTime - startTime));
accessLogMapper.insertSelective(log);
}
public void init(FilterConfig fConfig) throws ServletException {
}
}
这个过滤器使用了注解@WebFilter(filterName = "accessLog", urlPatterns = "/api/*") 进行配置，指定了url进入规则，只有以/api/开头的url才能进入到此过滤器中。在doFilter方法中使用了自定义的ResponseWrapper对response进行封装。Controller接口走完之后获取到接口返回的数据并再次封装到response。
3. ResponseWrapper.java 类
import java.io.ByteArrayOutputStream;
import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
public class ResponseWrapper extends HttpServletResponseWrapper {
private ByteArrayOutputStream buffer = null;
private ServletOutputStream out = null;
private PrintWriter writer = null;
public ResponseWrapper(HttpServletResponse response) throws IOException{
super(response);
buffer = new ByteArrayOutputStream();
out = new WapperedOutputStream(buffer);
writer = new PrintWriter(new OutputStreamWriter(buffer, "UTF-8"));
}
//重载父类获取outputstream的方法
@Override
public ServletOutputStream getOutputStream() throws IOException {
return out;
}
@Override
public PrintWriter getWriter() throws IOException {
return writer;
}
@Override
public void flushBuffer() throws IOException {
if (out != null) {
out.flush();
}
if (writer != null) {
writer.flush();
}
}
@Override
public void reset() {
buffer.reset();
}
public String getResponseData(String charset) throws IOException {
flushBuffer();//将out、writer中的数据强制输出到WapperedResponse的buffer里面，否则取不到数据
byte[] bytes = buffer.toByteArray();
try {
return new String(bytes, "UTF-8");
} catch (UnsupportedEncodingException e) {
return "";
}
}
//内部类，对ServletOutputStream进行包装，指定输出流的输出端
private class WapperedOutputStream extends ServletOutputStream {
private ByteArrayOutputStream bos = null;
public WapperedOutputStream(ByteArrayOutputStream stream) throws IOException {
bos = stream;
}
//将指定字节写入输出流bos
@Override
public void write(int b) throws IOException {
bos.write(b);
}
@Override
public boolean isReady() {
// TODO Auto-generated method stub
return false;
}
@Override
public void setWriteListener(WriteListener listener) {
// TODO Auto-generated method stub
}
}
}
以上这篇解决使用@ResponseBody后返回500错误的问题就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持呐喊教程。
声明：本文内容来源于网络，版权归原作者所有，内容由互联网用户自发贡献自行上传，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任。如果您发现有涉嫌版权的内容，欢迎发送邮件至：notice#nhooo.com（发邮件时，请将#更换为@）进行举报，并提供相关证据，一经查实，本站将立刻删除涉嫌侵权内容。