JAVA对象转JSON字符串时格式化日期_oracle clob转字符串

大家好，又见面了，我是你们的朋友全栈君。如果您正在找激活码,请点击查看最新教程,关注关注公众号 “全栈程序员社区” 获取激活教程,可能之前旧版本教程已经失效.最新Idea2022.1教程亲测有效,一键激活。

Jetbrains全系列IDE使用 1年只要46元 售后保障 童叟无欺

本案例所有代码均为原创，使用Java1.8类库编写，没有借鉴其他类似工具库和网上论坛博客，也许没有经过充分测试，可能出现未知bug，仅供参考学习使用。

Java对象就像一个文件夹一样，没有办法知道其深度，所以采用了递归。

性能方面没有测试，个人认为没有特别耗费性能的地方，除非你的对象包含很多层级。

它可以支持null，字符串，数字、日期、集合、数组以及自定义对象 等多种数据类型，包括以上任意类型的多层嵌套。

另外对于存储基本类型元素的数组而言，实在没有更好的处理办法，因此占用了很多代码行数。

源码不多，如下：

package com.duyi.boot.utils;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.*;

/** * @author qiaoao * @description: * @date 2021/7/29 18:10 */
public class JsonUtil { 
   

    private static JsonUtil util = new JsonUtil();

    public static String toJsonStr(Object obj) { 
   
        return util.parseObj(obj, new StringBuilder());
    }

    private String parseObj(Object obj, StringBuilder builder) { 
   
        if (builder == null) { 
   
            throw new UnsupportedOperationException("builder can not be null");
        }
        if (obj == null) { 
   
            return builder.append("\"null\"").toString();
        }
        Class clazz = obj.getClass();
        if (Collection.class.isAssignableFrom(clazz)) { 
   
            Iterator iterator = ((Collection) obj).iterator();
            builder.append("[");
            while (iterator.hasNext()) { 
   
                parseObj(iterator.next(), builder);
                if (iterator.hasNext())
                    builder.append(",");
            }
            builder.append("]");
        } else if (Map.class.isAssignableFrom(clazz)) { 
   
            //如果是map，key一定且必须是String类型，如果是对象，给他toString()
            Map map = ((Map) obj);
            Iterator iterator = map.keySet().iterator();
            builder.append("{");
            while (iterator.hasNext()) { 
   
                Object key = iterator.next();
                builder.append("\"");
                builder.append(key);
                builder.append("\":");
                parseObj(map.get(key), builder);
                if (iterator.hasNext())
                    builder.append(",");
            }
            builder.append("}");
        } else if (clazz.isArray()) { 
   
            //数组
            /** * 虽然int[]类型的数组可以通过：Arrays.stream((int[]) obj).boxed().collect(Collectors.toList()); * 转化为集合，但Arrays.stream()方法不支持char[] byte[] boolean[] float[] */
            builder.append("[");
            if (obj instanceof int[]) { 
   
                arrayHandle((int[]) obj, builder);
            } else if (obj instanceof byte[]) { 
   
                arrayHandle((byte[]) obj, builder);
            } else if (obj instanceof char[]) { 
   
                arrayHandle((char[]) obj, builder);
            } else if (obj instanceof long[]) { 
   
                arrayHandle((long[]) obj, builder);
            } else if (obj instanceof float[]) { 
   
                arrayHandle((float[]) obj, builder);
            } else if (obj instanceof short[]) { 
   
                arrayHandle((short[]) obj, builder);
            } else if (obj instanceof double[]) { 
   
                arrayHandle((double[]) obj, builder);
            } else if (obj instanceof boolean[]) { 
   
                arrayHandle((boolean[]) obj, builder);
            } else if (obj instanceof Object[]) { 
   
                List<Object> list = Arrays.asList((Object[]) obj);
                for (int i = 0; i < list.size(); i++) { 
   
                    parseObj(list.get(i), builder);
                    if (i < list.size() - 1) { 
   
                        builder.append(",");
                    }
                }
            } else { 
   
                throw new UnsupportedOperationException(obj.getClass().toString());
            }
            builder.append("]");
        } else if (String.class.isAssignableFrom(clazz) || Date.class.isAssignableFrom(clazz)) { 
   
            builder.append("\"");
            builder.append(obj);
            builder.append("\"");
        } else if (Number.class.isAssignableFrom(clazz) || Boolean.class.isAssignableFrom(clazz)) { 
   
            builder.append(obj);
        } else { 
   
            //自定义的实体类
            Field[] fields = clazz.getDeclaredFields();
            builder.append("{");
            for (int i = 0; i < fields.length; i++) { 
   
                Field field = fields[i];
                if (Modifier.isPrivate(field.getModifiers())) { 
   
                    field.setAccessible(true);
                }
                builder.append("\"");
                builder.append(field.getName());
                builder.append("\":");
                Object value = null;
                try { 
   
                    value = field.get(obj);
                } catch (IllegalAccessException e) { 
   
                    e.printStackTrace();
                }
                parseObj(value, builder);
                if (i < fields.length - 1) { 
   
                    builder.append(",");
                }
            }
            builder.append("}");
        }
        return builder.toString();
    }

    private void arrayHandle(int[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(byte[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(char[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(long[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(float[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(short[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(double[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }

    private void arrayHandle(boolean[] arr, StringBuilder builder) { 
   
        for (int i = 0; i < arr.length; i++) { 
   
            parseObj(arr[i], builder);
            if (i < arr.length - 1) { 
   
                builder.append(",");
            }
        }
    }
}

以下为测试代码：

import java.util.*;

/** * @author qiaoao * @description: * @date 2021/7/30 14:06 */
public class Demo { 
   
    private long aLong;
    private int aInt;
    public short aShort;
    private static boolean isAlive;
    private String name;
    private byte[] bytes;
    private Date[] dates;
    private int[][][] superIntArr;
    private String[][] strings;
    private List<Map<Integer,String>> list;
    private Set<int[]> set;
    private Map<String,List<int[]>> map;

    public static void main(String[] args) throws IllegalAccessException { 
   
        Demo demo = Demo.getObj();
        String json = JsonUtil.toJsonStr(demo);
        System.out.println(json);
    }

    public static Demo getObj(){ 
   
        Demo demo = new Demo();
        demo.setaLong(1000012L);
        demo.setaInt(120);
        Demo.setIsAlive(true);
        demo.setaShort((short)78);
        demo.setName("Demo Test");
        byte[] bytes = new byte[2];
        bytes[0] = 1;
        bytes[1] = 127;
        demo.setBytes(bytes);
        Date[] dates = new Date[3];
        dates[1] = new Date();
        demo.setDates(dates);
        int[][][] superIntArr = new int[2][2][2];
        for (int i = 0;i<superIntArr.length;i++){ 
   
            for (int j = 0;j<superIntArr[i].length;j++){ 
   
                for (int k = 0;k<superIntArr[j].length;k++){ 
   
                    superIntArr[i][j][k] = (int)(Math.random()*100);
                }
            }
        }
        demo.setSuperIntArr(superIntArr);
        String[][] strings = new String[5][2];
        for (int i = 0; i < strings.length; i++) { 
   
            for (int j = 0; j < strings[i].length; j++) { 
   
                strings[i][j] = String.valueOf(Math.random());
            }
        }
        demo.setStrings(strings);
        List<Map<Integer,String>> list = new LinkedList<>();
        Map<Integer,String> map = new Hashtable<>();
        map.put(1,"demo1");
        map.put(2,"demo2");
        map.put(3,"demo3");
        Map<Integer,String> map2 = new Hashtable<>();
        map2.put(12,"demo12");
        map2.put(22,"demo22");
        map2.put(32,"demo32");
        list.add(map);
        list.add(map2);
        demo.setList(list);
        Set<int[]> set = new HashSet<>();
        for (int i = 0;i<5;i++){ 
   
            int len = (int)(Math.random()*10)+2;
            int[] tempArr = new int[len];
            for (int j = 0; j < tempArr.length; j++) { 
   
                tempArr[j] = 100 - j;
            }
            set.add(tempArr);
        }
        demo.setSet(set);
        Map<String,List<int[]>> maps = new LinkedHashMap<>();
        for (int i = 0;i<=3;i++){ 
   
            List<int[]> tempList = new Stack<>();
            for (int j = 20;j>=0;j--){ 
   
                int[] hh = new int[5];
                for (int k = 0; k < hh.length; k++) { 
   
                    hh[k] = k+j;
                }
                tempList.add(hh);
            }
            maps.put("list"+i,tempList);
        }
        demo.setMap(maps);
        return demo;
    }

    public static void setIsAlive(boolean isAlive) { 
   
        Demo.isAlive = isAlive;
    }

    public void setaLong(long aLong) { 
   
        this.aLong = aLong;
    }

    public void setaInt(int aInt) { 
   
        this.aInt = aInt;
    }

    public void setaShort(short aShort) { 
   
        this.aShort = aShort;
    }

    public void setName(String name) { 
   
        this.name = name;
    }

    public void setBytes(byte[] bytes) { 
   
        this.bytes = bytes;
    }

    public void setDates(Date[] dates) { 
   
        this.dates = dates;
    }

    public void setSuperIntArr(int[][][] superIntArr) { 
   
        this.superIntArr = superIntArr;
    }

    public void setStrings(String[][] strings) { 
   
        this.strings = strings;
    }

    public void setList(List<Map<Integer, String>> list) { 
   
        this.list = list;
    }

    public void setSet(Set<int[]> set) { 
   
        this.set = set;
    }

    public void setMap(Map<String, List<int[]>> map) { 
   
        this.map = map;
    }
}

执行结果如下：

{ 
   "aLong":1000012,"aInt":120,"aShort":78,"isAlive":true,"name":"Demo Test","bytes":[1,127],"dates":["null","Fri Jul 30 15:25:35 CST 2021","null"],"superIntArr":[[[11,99],[47,20]],[[20,72],[59,49]]],"strings":[["0.11307908409828815","0.22341871804534985"],["0.5005992982006673","0.5893604912974005"],["0.6892806476807729","0.4169059518233631"],["0.650889741691504","0.8702143841026739"],["0.26192826894369403","0.31877430959379016"]],"list":[{ 
   "3":"demo3","2":"demo2","1":"demo1"},{ 
   "32":"demo32","12":"demo12","22":"demo22"}],"set":[[100,99,98],[100,99,98,97,96,95],[100,99,98,97,96,95,94,93,92,91],[100,99,98,97,96,95,94,93],[100,99,98,97,96,95,94,93]],"map":{ 
   "list0":[[20,21,22,23,24],[19,20,21,22,23],[18,19,20,21,22],[17,18,19,20,21],[16,17,18,19,20],[15,16,17,18,19],[14,15,16,17,18],[13,14,15,16,17],[12,13,14,15,16],[11,12,13,14,15],[10,11,12,13,14],[9,10,11,12,13],[8,9,10,11,12],[7,8,9,10,11],[6,7,8,9,10],[5,6,7,8,9],[4,5,6,7,8],[3,4,5,6,7],[2,3,4,5,6],[1,2,3,4,5],[0,1,2,3,4]],"list1":[[20,21,22,23,24],[19,20,21,22,23],[18,19,20,21,22],[17,18,19,20,21],[16,17,18,19,20],[15,16,17,18,19],[14,15,16,17,18],[13,14,15,16,17],[12,13,14,15,16],[11,12,13,14,15],[10,11,12,13,14],[9,10,11,12,13],[8,9,10,11,12],[7,8,9,10,11],[6,7,8,9,10],[5,6,7,8,9],[4,5,6,7,8],[3,4,5,6,7],[2,3,4,5,6],[1,2,3,4,5],[0,1,2,3,4]],"list2":[[20,21,22,23,24],[19,20,21,22,23],[18,19,20,21,22],[17,18,19,20,21],[16,17,18,19,20],[15,16,17,18,19],[14,15,16,17,18],[13,14,15,16,17],[12,13,14,15,16],[11,12,13,14,15],[10,11,12,13,14],[9,10,11,12,13],[8,9,10,11,12],[7,8,9,10,11],[6,7,8,9,10],[5,6,7,8,9],[4,5,6,7,8],[3,4,5,6,7],[2,3,4,5,6],[1,2,3,4,5],[0,1,2,3,4]],"list3":[[20,21,22,23,24],[19,20,21,22,23],[18,19,20,21,22],[17,18,19,20,21],[16,17,18,19,20],[15,16,17,18,19],[14,15,16,17,18],[13,14,15,16,17],[12,13,14,15,16],[11,12,13,14,15],[10,11,12,13,14],[9,10,11,12,13],[8,9,10,11,12],[7,8,9,10,11],[6,7,8,9,10],[5,6,7,8,9],[4,5,6,7,8],[3,4,5,6,7],[2,3,4,5,6],[1,2,3,4,5],[0,1,2,3,4]]}}

可以放到 json 在线格式化页面里检验：