封装fastjson为spring mvc的json view

可以将其中的main方法删掉。测试用的。我测试的结果是，jackson比fastjson快。

fastjson是1.1.36

jackson是2.2.3

jdk是1.7.40，client

cpu是intel i3

内存4g

package org.springframework.web.servlet.view.json;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.io.StringReader;

import java.io.StringWriter;

import java.nio.charset.Charset;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.springframework.util.CollectionUtils;

import org.springframework.validation.BindingResult;

import org.springframework.web.servlet.view.AbstractView;

import com.alibaba.fastjson.JSON;

import com.alibaba.fastjson.parser.Feature;

import com.alibaba.fastjson.serializer.SerializerFeature;

import com.fasterxml.jackson.core.JsonFactory;

import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.core.JsonParseException;

import com.fasterxml.jackson.core.JsonProcessingException;

import com.fasterxml.jackson.core.type.TypeReference;

import com.fasterxml.jackson.databind.JsonMappingException;

import com.fasterxml.jackson.databind.MappingIterator;

import com.fasterxml.jackson.databind.ObjectMapper;

import com.google.common.collect.Lists;

import com.google.common.collect.Maps;

import com.google.common.collect.Sets;

import com.test.User;

public class MappingFastJsonView extends AbstractView {

    

    /**

     * Default content type: "application/json".

     * Overridable through {@link #setContentType}.

     */

    public static final String DEFAULT_CONTENT_TYPE = "application/json";

private String encoding = "UTF-8";

    

    private String jsonPrefix;

private Boolean prettyPrint;

private Set<String> modelKeys;

private boolean extractValueFromSingleKeyModel = false;

private boolean disableCaching = true;

private boolean updateContentLength = false;

/**

     * Construct a new {@code MappingFastJsonView}, setting the content type to {@code application/json}.

     */

    public MappingFastJsonView() {

        setContentType(DEFAULT_CONTENT_TYPE);

        setExposePathVariables(false);

    }

    

    public String getEncoding() {

        return encoding;

    }

public void setEncoding(String encoding) {

        this.encoding = encoding;

    }

/**

     * Specify a custom prefix to use for this view's JSON output.

     * Default is none.

     * @see #setPrefixJson

     */

    public void setJsonPrefix(String jsonPrefix) {

        this.jsonPrefix = jsonPrefix;

    }

/**

     * Indicates whether the JSON output by this view should be prefixed with <tt>"{} && "</tt>.

     * Default is {@code false}.

     * <p>Prefixing the JSON string in this manner is used to help prevent JSON Hijacking.

     * The prefix renders the string syntactically invalid as a script so that it cannot be hijacked.

     * This prefix does not affect the evaluation of JSON, but if JSON validation is performed

     * on the string, the prefix would need to be ignored.

     * @see #setJsonPrefix

     */

    public void setPrefixJson(boolean prefixJson) {

//        if (prefixJson) {

//            if (jsonPrefix == null) {

//                jsonPrefix = "{} && ";

//            }

//        }

        this.jsonPrefix = (prefixJson ? "{} && " : null);

    }

/**

     * Whether to use the default pretty printer when writing JSON.

     * This is a shortcut for setting up an {@code JSON}

     * <p>The default value is {@code false}.

     */

    public void setPrettyPrint(boolean prettyPrint) {

        this.prettyPrint = prettyPrint;

    }

/**

     * Set the attribute in the model that should be rendered by this view.

     * When set, all other model attributes will be ignored.

     */

    public void setModelKey(String modelKey) {

        this.modelKeys = Collections.singleton(modelKey);

    }

/**

     * Set the attributes in the model that should be rendered by this view.

     * When set, all other model attributes will be ignored.

     */

    public void setModelKeys(Set<String> modelKeys) {

        this.modelKeys = modelKeys;

    }

/**

     * Return the attributes in the model that should be rendered by this view.

     */

    public final Set<String> getModelKeys() {

        return this.modelKeys;

    }

    

    /**

     * Set whether to serialize models containing a single attribute as a map or whether to

     * extract the single value from the model and serialize it directly.

     * <p>The effect of setting this flag is similar to using {@code MappingJacksonHttpMessageConverter}

     * with an {@code @ResponseBody} request-handling method.

     * <p>Default is {@code false}.

     */

    public void setExtractValueFromSingleKeyModel(boolean extractValueFromSingleKeyModel) {

        this.extractValueFromSingleKeyModel = extractValueFromSingleKeyModel;

    }

/**

     * Disables caching of the generated JSON.

     * <p>Default is {@code true}, which will prevent the client from caching the generated JSON.

     */

    public void setDisableCaching(boolean disableCaching) {

        this.disableCaching = disableCaching;

    }

/**

     * Whether to update the 'Content-Length' header of the response. When set to

     * {@code true}, the response is buffered in order to determine the content

     * length and set the 'Content-Length' header of the response.

     * <p>The default setting is {@code false}.

     */

    public void setUpdateContentLength(boolean updateContentLength) {

        this.updateContentLength = updateContentLength;

    }

    

    @Override

    protected void prepareResponse(HttpServletRequest request, HttpServletResponse response) {

        setResponseContentType(request, response);

        response.setCharacterEncoding(encoding);

        if (this.disableCaching) {

            response.addHeader("Pragma", "no-cache");

            response.addHeader("Cache-Control", "no-cache, no-store, max-age=0");

            response.addDateHeader("Expires", 1L);

        }

    }

    

    @Override

    protected void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response)

            throws Exception {

        OutputStream stream = (this.updateContentLength ? createTemporaryOutputStream() : response.getOutputStream());

        Object value = filterModel(model);

        writeContent(stream, value, this.jsonPrefix);

        if (this.updateContentLength) {

            writeToResponse(response, (ByteArrayOutputStream) stream);

        }

    }

/**

     * Filter out undesired attributes from the given model.

     * The return value can be either another {@link Map} or a single value object.

     * <p>The default implementation removes {@link BindingResult} instances and entries

     * not included in the {@link #setRenderedAttributes renderedAttributes} property.

     * @param model the model, as passed on to {@link #renderMergedOutputModel}

     * @return the value to be rendered

     */

    protected Object filterModel(Map<String, Object> model) {

        Map<String, Object> result = new HashMap<String, Object>(model.size());

        Set<String> renderedAttributes = (!CollectionUtils.isEmpty(this.modelKeys) ? this.modelKeys : model.keySet());

        for (Map.Entry<String, Object> entry : model.entrySet()) {

            if (!(entry.getValue() instanceof BindingResult) && renderedAttributes.contains(entry.getKey())) {

                result.put(entry.getKey(), entry.getValue());

            }

        }

        return (this.extractValueFromSingleKeyModel && result.size() == 1 ? result.values().iterator().next() : result);

    }

/**

     * Write the actual JSON content to the stream.

     * @param stream the output stream to use

     * @param value the value to be rendered, as returned from {@link #filterModel}

     * @param jsonPrefix the prefix for this view's JSON output

     * (as indicated through {@link #setJsonPrefix}/{@link #setPrefixJson})

     * @throws IOException if writing failed

     */

    protected void writeContent(OutputStream stream, Object value, String jsonPrefix) throws IOException {

        

        List<SerializerFeature> list = new ArrayList<SerializerFeature>();

        if (prettyPrint != null && prettyPrint) {

            list.add(SerializerFeature.PrettyFormat);

        }

        

        SerializerFeature[] features = new SerializerFeature[list.size()];

        list.toArray(features);

        

        byte[] jsonBytes = JSON.toJSONBytes(value, features);

        

        if (jsonPrefix != null) {//此处亦可字符串相加，然后转成字节数组

            byte[] prefixBytes = jsonPrefix.getBytes(Charset.forName("UTF-8"));

            int prefixLength = prefixBytes.length;

            int jsonLength = jsonBytes.length;

            byte[] finalJsonBytes = new byte[prefixLength + jsonLength];

            

            System.arraycopy(prefixBytes, 0, finalJsonBytes, 0, prefixLength);

            System.arraycopy(jsonBytes, 0, finalJsonBytes, prefixLength, jsonLength);

            stream.write(finalJsonBytes);

        } else {

            stream.write(jsonBytes);

        }

        

        stream.flush();

    }

    

    public static void main(String[] args) {

        

        

        List<User> users = Lists.newArrayList();

        for (int j = 0; j < 10; j++) {

            User value = new User();

            value.setAddress("asdfjklasdjf");

            value.setAge(22);

            value.setGender(1);

            value.setPassword("jkljklj");

            value.setUserName("");

            

            List<String> strList = Lists.newArrayList();

            Map<String, String> strMap = Maps.newHashMap();

            Set<Integer> setInt = Sets.newHashSet();

            

            for (int i = 0; i < 10; i++) {

                strList.add("a" + i);

                strMap.put("a" + i, "a" + i);

                setInt.add(i);

            }

            

            value.setSetInt(setInt);

            value.setStrList(strList);

            value.setStrMap(strMap);

            users.add(value);

        }

        

        int times = 1;

//        long d = System.currentTimeMillis();

//        String jsonPrefix = "aaa{}";

//        

//        for (int i = 0; i < times; i++) {

//            byte[] jsonBytes = JSON.toJSONBytes(value);

//            byte[] prefixBytes = jsonPrefix.getBytes(Charset.forName("UTF-8"));

//            int prefixLength = prefixBytes.length;

//            int jsonLength = jsonBytes.length;

//            byte[] finalJsonBytes = new byte[prefixLength + jsonLength];

//            

//            System.arraycopy(prefixBytes, 0, finalJsonBytes, 0, prefixLength);

//            System.arraycopy(jsonBytes, 0, finalJsonBytes, prefixLength, jsonLength);

//        }

//        System.out.println(System.currentTimeMillis() - d);

        

        String json = "";

        String json2 = "";

        long d2 = System.currentTimeMillis();

        //String jsonPrefix2 = "aaa{}";

        for (int i = 0; i < times; i++) {

            json = JSON.toJSONString(users);

            

//            jsonBytes = jsonPrefix2 + jsonBytes;

//            

//            byte[] prefixBytes = jsonBytes.getBytes(Charset.forName("UTF-8"));

            

        }

        System.out.println("fastjson parser :" + (System.currentTimeMillis() - d2));

        

        ObjectMapper mapper = new ObjectMapper();

        

        //org.codehaus.jackson.map.ObjectMapper mapper = new org.codehaus.jackson.map.ObjectMapper();

        

        long d3 = System.currentTimeMillis();

        //String jsonPrefix3 = "aaa{}";

        for (int i = 0; i < times; i++) {

            //String jsonBytes = null;

            try {

                //StringWriter writer = new StringWriter();

                //JsonGenerator generator = new JsonFactory().createGenerator(writer);

                //mapper.writeValue(writer, value);

                //jsonBytes = writer.toString();

                json2 = mapper.writeValueAsString(users);

                //mapper.readValue(new StringReader(""), class1);

            } catch (Exception e) {

                e.printStackTrace();

            }

            

//            jsonBytes = jsonPrefix3 + jsonBytes;

//            

//            byte[] prefixBytes = jsonBytes.getBytes(Charset.forName("UTF-8"));

            

        }

        System.out.println("jackson parser :" + (System.currentTimeMillis() - d3));

        

        long d5 = System.currentTimeMillis();

        for (int i = 0; i < times; i++) {

            JSON.parseArray(json, User.class);

        }

        System.out.println("fastjson deserializer :" + (System.currentTimeMillis() - d5));

        

        long d4 = System.currentTimeMillis();

        for (int i = 0; i < times; i++) {

            try {

                //List<User> userList = Lists.newArrayList();

                mapper.readValue(json2, new TypeReference<List<User>>() {});

//                List<User> userList = Lists.newArrayList();

//                for (;iterator.hasNext();) {

//                    userList.add(iterator.nextValue());

//                }

                //System.out.println(userList);

            } catch (JsonParseException e) {

                e.printStackTrace();

            } catch (JsonMappingException e) {

                e.printStackTrace();

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

        System.out.println("jackson deserializer :" + (System.currentTimeMillis() - d4));

        

        

    }

}

package com.test;

import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class User {
    private String userName;
    private String address;
    private int age;
    private int gender;
    private String password;
    
    private List<String> strList;
    private Map<String, String> strMap;
    
    private Set<Integer> setInt;
    
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public int getGender() {
        return gender;
    }
    public void setGender(int gender) {
        this.gender = gender;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public List<String> getStrList() {
        return strList;
    }
    public void setStrList(List<String> strList) {
        this.strList = strList;
    }
    public Map<String, String> getStrMap() {
        return strMap;
    }
    public void setStrMap(Map<String, String> strMap) {
        this.strMap = strMap;
    }
    public Set<Integer> getSetInt() {
        return setInt;
    }
    public void setSetInt(Set<Integer> setInt) {
        this.setInt = setInt;
    }
    
    
}