SpringMVC4直接返回String乱码

过滤器我就不说了。

如果你是要返回一个String的话，比较蛋疼，因为很少直接返回String，所以我最近才发现这个问题，在你的Spring mvc的Controller上加上：

@RequestMapping(value = "test", produces = "application/json; charset=utf-8")

或者你可以做点更高级的事：

MyStringHttpMessageConverter.java：

package cn.dubby.what.util;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.util.StreamUtils;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

/**
* Created by dubby on 16/5/11.
*/
public class MyStringHttpMessageConverter extends AbstractHttpMessageConverter<String> {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

private final Charset defaultCharset;

private final List<Charset> availableCharsets;

private boolean writeAcceptCharset = true;

/**
* A default constructor that uses {@code "ISO-8859-1"} as the default charset.
*
* @see #MyStringHttpMessageConverter(Charset)
*/
public MyStringHttpMessageConverter() {
this(DEFAULT_CHARSET);
}

/**
* A constructor accepting a default charset to use if the requested content
* type does not specify one.
*/
public MyStringHttpMessageConverter(Charset defaultCharset) {
super(new MediaType("text", "plain", defaultCharset), MediaType.ALL);
this.defaultCharset = defaultCharset;
this.availableCharsets = new ArrayList<Charset>(Charset.availableCharsets().values());
}

/**
* Indicates whether the {@code Accept-Charset} should be written to any outgoing request.
* <p>Default is {@code true}.
*/
public void setWriteAcceptCharset(boolean writeAcceptCharset) {
this.writeAcceptCharset = writeAcceptCharset;
}

@Override
public boolean supports(Class<?> clazz) {
return String.class.equals(clazz);
}

@Override
protected String readInternal(Class<? extends String> clazz, HttpInputMessage inputMessage) throws IOException {
Charset charset = getContentTypeCharset(inputMessage.getHeaders().getContentType());
return StreamUtils.copyToString(inputMessage.getBody(), charset);
}

@Override
protected Long getContentLength(String str, MediaType contentType) {
Charset charset = getContentTypeCharset(contentType);
try {
return (long) str.getBytes(charset.name()).length;
} catch (UnsupportedEncodingException ex) {
// should not occur
throw new IllegalStateException(ex);
}
}

@Override
protected void writeInternal(String str, HttpOutputMessage outputMessage) throws IOException {
if (this.writeAcceptCharset) {
outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
}
Charset charset = getContentTypeCharset(outputMessage.getHeaders().getContentType());
StreamUtils.copy(str, charset, outputMessage.getBody());
}

/**
* Return the list of supported {@link Charset}s.
* <p>By default, returns {@link Charset#availableCharsets()}.
* Can be overridden in subclasses.
*
* @return the list of accepted charsets
*/
protected List<Charset> getAcceptedCharsets() {
return this.availableCharsets;
}

private Charset getContentTypeCharset(MediaType contentType) {
if (contentType != null && contentType.getCharSet() != null) {
return contentType.getCharSet();
} else {
return this.defaultCharset;
}
}
}

然后在Spring mvc的配置文件上加上：

<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<bean class="cn.dubby.what.util.MyStringHttpMessageConverter"/>
</mvc:annotation-driven>