Java处理JSON数据有三个比较流行的类库FastJSON、Gson和Jackson。本文将测试这三个类库在JSON序列化和反序列化的方面表现，主要测试JSON序列化和反序列化的速度。为了防止由于内存导致测试结果出现偏差，测试中对JVM内存配置-Xmx4g -Xms4g。
JSON序列化(Object => JSON)
测试样本数量为100000个，为了保证每个类库在测试中都能处理同一个样本，先把样本Java对象保存在文件中。每个类库测试3次，每次循环测试10遍，去掉最快速度和最慢速度，对剩下的8遍求平均值作为最终的速，取3次测试中最好的平均速度作为最终的测试数据。
| 类库 | 样本数量 | 执行次数 | 最长时间(毫秒) | 最短时间(毫秒) | 平均时间(毫秒) |
|---|---|---|---|---|---|
| FastJSON | 100000 | 10 | 2291.22 | 1416.70 | 1454.93 |
| Jackson | 100000 | 10 | 1980.92 | 841.91 | 880.82 |
| Gson | 100000 | 10 | 2383.02 | 1469.08 | 1520.38 |
从测试数据可知，FastJSON和GsonJSON序列化的速度差不多，Jackson是最快的（用时Gson少大约600毫秒）。
JSON反序列化(JSON => Object)
测试样本数量为100000个，为了保证每个类库在测试中都能处理同一个样本，先把样本JSON对象保存在文件中。每个类库测试3次，每次循环测试10遍，去掉最快速度和最慢速度，对剩下的8遍求平均值作为最终的速，取3次测试中最好的平均速度作为最终的测试数据。
| 类库 | 样本数量 | 执行次数 | 最长时间(毫秒) | 最短时间(毫秒) | 平均时间(毫秒) |
|---|---|---|---|---|---|
| FastJSON | 100000 | 10 | 7942.31 | 6340.55 | 6526.41 |
| Jackson | 100000 | 10 | 7957.22 | 6623.85 | 6815.41 |
| Gson | 100000 | 10 | 8235.15 | 7006.06 | 7364.75 |
从测试数据可知，三个类库在反序列化上性能比较接近，Gson稍微差一些。
总结
把Java对象JSON序列化，Jackson速度最快，在测试中比Gson快接近50%，FastJSON和Gson速度接近。
把JSON反序列化成Java对象，FastJSON、Jackson速度接近，Gson速度稍慢，不过差距很小。
样本对象
样本对象包括Boolean、Int、Long、Double、Date、String、List和Map字段，其中List长度和Map的Key数量可以根据需要改
import java.util.ArrayList;
import java.util.Date; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Random; /** * 该类提供生成样本的元数据 * @author accountwcx@qq.com * */ public class DataBuilder { private static final String[] chars = new String[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" }; private static final int charNum = 62; // 样本String最大长度 private static final int maxStrLength = 100; // 样本String默认长度 private static final int defaultStrLength = 50; // 样本List最大长度 private static final int maxListSize = 100; // 样本List默认长度 private static final int defaultListSize = 10; // 样本Map最大Key数量 private static final int maxMapSize = 100; // 样本Map默认Key数量 private static final int defaultMapSize = 10; // 样本Map中Value的数据类型 private static final String[] types = new String[] { "boolean", "int", "long", "double", "date", "string"}; private static final int typeNum = 6; private static final Random random = new Random(); /** * 生成随机长度的字符串 * @return 字符串 */ public static String randomString(){ return randomString(random.nextInt(maxStrLength)); } /** * 生成指定长度的字符串 * @param len 字符串长度 * @return */ public static String randomString(int len) { if (len < 1 || len > maxStrLength) { // 如果字符串长度超出范围，使用默认长度 len = defaultStrLength; } StringBuilder sb = new StringBuilder(len); for (int i = 0; i < len; i++) { sb.append(chars[random.nextInt(charNum)]); } return sb.toString(); } /** * 生成List样本，List中元素的数量随机 * @return */ public static List<String> randomStringList() { return randomStringList(random.nextInt(maxListSize)); } /** * 生成List样本 * @param size List中元素的数量 * @return */ public static List<String> randomStringList(int size) { if (size < 1 || size > maxListSize) { size = defaultListSize; } List<String> list = new ArrayList<String>(); for (int i = 0; i < size; i++) { list.add(randomString(random.nextInt(maxStrLength))); } return list; } /** * 生成随机Map样本，样本中key的数量随机 * @return */ public static Map<String, Object> randomMap() { return randomMap(random.nextInt(maxMapSize)); } /** * 生成随机Map样本 * @param size 样本中key的数量 * @return */ public static Map<String, Object> randomMap(int size) { if (size < 1 || size > maxMapSize) { size = defaultMapSize; } Map<String, Object> map = new HashMap<String, Object>(); for (int i = 0; i < size; i++) { String type = types[random.nextInt(typeNum)]; if ("boolean".equals(type)) { map.put("key" + i, random.nextBoolean()); } else if ("int".equals(type)) { map.put("key" + i, random.nextInt()); } else if ("long".equals(type)) { map.put("key" + i, random.nextLong()); } else if ("double".equals(type)) { map.put("key" + i, random.nextDouble()); } else if ("date".equals(type)) { map.put("key" + i, new Date()); } else if ("string".equals(type)) { map.put("key" + i, randomString(random.nextInt(maxStrLength))); } } return map; } }
import java.io.Serializable;
import java.util.Date; import java.util.List; import java.util.Map; import java.util.Random; /** * 样本对象 * @author accountwcx@qq.com * */ public class SampleEntity implements Serializable { private static final long serialVersionUID = -1520171788566678009L; private Boolean fieldBoolean; private Integer fieldInt; private Long fieldLong; private Double fieldDouble; private Date fieldDate; private String fieldStr; private List<String> fieldList; private Map<String, Object> fieldMap; /** * 随机样本 */ public SampleEntity() { Random random = new Random(); fieldBoolean = random.nextBoolean(); fieldInt = random.nextInt(); fieldLong = random.nextLong(); fieldDouble = random.nextDouble(); fieldDate = new Date(); fieldStr = DataBuilder.randomString(); fieldList = DataBuilder.randomStringList(); fieldMap = DataBuilder.randomMap(); } /** * 指定List元素数量和Map元素数量的样本 * @param listSize List元素数量 * @param mapKeyNum Map元素数量 */ public SampleEntity(int listSize, int mapKeyNum) { Random random = new Random(); fieldBoolean = random.nextBoolean(); fieldInt = random.nextInt(); fieldLong = random.nextLong(); fieldDouble = random.nextDouble(); fieldDate = new Date(); fieldStr = DataBuilder.randomString(); fieldList = DataBuilder.randomStringList(listSize); fieldMap = DataBuilder.randomMap(mapKeyNum); } public Boolean getFieldBoolean() { return fieldBoolean; } public void setFieldBoolean(Boolean fieldBoolean) { this.fieldBoolean = fieldBoolean; } public Integer getFieldInt() { return fieldInt; } public void setFieldInt(Integer fieldInt) { this.fieldInt = fieldInt; } public Long getFieldLong() { return fieldLong; } public void setFieldLong(Long fieldLong) { this.fieldLong = fieldLong; } public Double getFieldDouble() { return fieldDouble; } public void setFieldDouble(Double fieldDouble) { this.fieldDouble = fieldDouble; } public Date getFieldDate() { return fieldDate; } public void setFieldDate(Date fieldDate) { this.fieldDate = fieldDate; } public String getFieldStr() { return fieldStr; } public void setFieldStr(String fieldStr) { this.fieldStr = fieldStr; } public List<String> getFieldList() { return fieldList; } public void setFieldList(List<String> fieldList) { this.fieldList = fieldList; } public Map<String, Object> getFieldMap() { return fieldMap; } public void setFieldMap(Map<String, Object> fieldMap) { this.fieldMap = fieldMap; } }
import java.io.BufferedReader;
import java.io.BufferedWriter; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.util.LinkedList; import java.util.List; import com.alibaba.fastjson.JSON; /** * 创建样本 * @author accountwcx@qq.com * */ public class SampleBuilder { public static void main(String[] args) { int sampleSize = 100000; String jsonDataPath = "d:\\samples_json.dat"; String objectDataPath = "d:\\samples_object.dat"; buildJsonSamples(sampleSize, 10, 10, jsonDataPath); buildObjectSamples(sampleSize, 10, 10, objectDataPath); } public static List<String> loadJSONSamples(String filePath) { List<String> list = new LinkedList<String>(); File file = new File(filePath); if (!file.exists()) { return list; } BufferedReader br = null; try { br = new BufferedReader(new FileReader(file)); String line = br.readLine(); while(line != null){ list.add(line); line = br.readLine(); } } catch (Exception e) { e.printStackTrace(); } finally { if (null != br) { try { br.close(); } catch (IOException e) { } } } return list; } @SuppressWarnings("unchecked") public static List<SampleEntity> loadSamples(String filePath) { List<SampleEntity> list = new LinkedList<SampleEntity>(); File file = new File(filePath); if (!file.exists()) { return list; } ObjectInputStream ois = null; try { ois = new ObjectInputStream(new FileInputStream(file)); list = (List<SampleEntity>) ois.readObject(); } catch (Exception e) { e.printStackTrace(); } finally { if (null != ois) { try { ois.close(); } catch (IOException e) { } } } return list; } /** * 创建样本 * * @param sampleSize 样本数量 * @param listSize 样本List长度 * @param mapKeyNum 样本Map的Key数量 * @return 样本List */ public static List<SampleEntity> buildSamples(int sampleSize, int listSize, int mapKeyNum) { List<SampleEntity> list = new LinkedList<SampleEntity>(); for (int i = 0; i < sampleSize; i++) { list.add(new SampleEntity(listSize, mapKeyNum)); } return list; } /** * 用默认参数创建样本，其中listSize默认为10，mapKeyNum默认为10。 * * @param sampleSize * @return 样本List */ public static List<SampleEntity> buildSamples(int sampleSize) { List<SampleEntity> list = new LinkedList<SampleEntity>(); for (int i = 0; i < sampleSize; i++) { list.add(new SampleEntity()); } return list; } /** * 创建样本，并把样本JSON序列化，保存到文件中。 * * @param sampleSize 样本数量 * @param listSize 样本List长度 * @param mapKeyNum 样本Map中Key的数量 * @param filePath 样本输出的文件路径 */ public static void buildJsonSamples(int sampleSize, int listSize, int mapKeyNum, String filePath) { File file = new File(filePath); File parent = file.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } if (file.exists()) { file.delete(); } List<SampleEntity> list = buildSamples(sampleSize, listSize, mapKeyNum); StringBuilder sb = new StringBuilder(); for (SampleEntity item : list) { sb.append(JSON.toJSONString(item)); sb.append("\n"); } BufferedWriter bw = null; try { file.createNewFile(); bw = new BufferedWriter(new FileWriter(file)); bw.write(sb.toString()); bw.flush(); } catch (IOException e) { e.printStackTrace(); } finally { if (null != bw) { try { bw.close(); } catch (IOException e) { } } } } public static void buildJsonSamples(int sampleSize, String filePath) { File file = new File(filePath); File parent = file.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } if (file.exists()) { file.delete(); } List<SampleEntity> list = buildSamples(sampleSize); StringBuilder sb = new StringBuilder(); for (SampleEntity item : list) { sb.append(JSON.toJSONString(item)); sb.append("\n"); } BufferedWriter bw = null; try { file.createNewFile(); bw = new BufferedWriter(new FileWriter(file)); bw.write(sb.toString()); bw.flush(); } catch (IOException e) { e.printStackTrace(); } finally { if (null != bw) { try { bw.close(); } catch (IOException e) { } } } } public static void buildObjectSamples(int sampleSize, String filePath) { List<SampleEntity> list = buildSamples(sampleSize); File file = new File(filePath); File parent = file.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } if (file.exists()) { file.delete(); } ObjectOutputStream oos = null; try { file.createNewFile(); oos = new ObjectOutputStream(new FileOutputStream(file)); oos.writeObject(list); } catch (IOException e) { e.printStackTrace(); } finally { if (null != oos) { try { oos.close(); } catch (IOException e) { } } } } /** * 生成样本对象，并保存到指定文件 * * @param sampleSize 样本大小 * @param listSize 样本中List字段长度 * @param mapKeyNum 样本中Map对象Key数量 * @param filePath 样本输出的路径 */ public static void buildObjectSamples(int sampleSize, int listSize, int mapKeyNum, String filePath) { List<SampleEntity> list = buildSamples(sampleSize, listSize, mapKeyNum); File file = new File(filePath); File parent = file.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } if (file.exists()) { file.delete(); } ObjectOutputStream oos = null; try { file.createNewFile(); oos = new ObjectOutputStream(new FileOutputStream(file)); oos.writeObject(list); } catch (IOException e) { e.printStackTrace(); } finally { if (null != oos) { try { oos.close(); } catch (IOException e) { } } } } }
from: http://www.voidcn.com/blog/ZHOU452840622/article/p-6094386.html