欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

JAVA中,各种数据转换为对象的原理

程序员文章站 2024-02-10 08:32:24
...

package com.it.code.req_string_map_obj;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
public class demo002 {

    /**
     * 把对象toString
     * 
     * @param object 对象
     * @return 对象转换为String的类型
     * @throws Exception
     */
    public static String toString(Object object)     {
        if (object == null) {
            return null;
        }
        StringBuffer sb = new StringBuffer();
        Class c = object.getClass();
        Method[] methods = c.getMethods();
        Field[] fields = c.getDeclaredFields();
        String fieldName, methodName;
        Method method;
        Field field;
        for (int i = 0; i < fields.length; i++) {
            field = fields[i];
            fieldName = field.getName();
            for (int j = 0; j < methods.length; j++) {
                method = methods[j];
                methodName = method.getName();
                if (methodName.toUpperCase().endsWith("GET" + fieldName.toUpperCase())) {
                    try {
                        sb.append(fieldName + "=" + method.invoke(object));
                    } catch (Exception e) {
                         System.out.println("映射新对象" + c + "失败,列名:" + fieldName + ",方法名:" + methodName + "/n" + e);
                    }
                    break;
                }
            }
            if (i < fields.length - 1) {
                sb.append(",");
            }
        }
        return sb.toString();
    }
    //测试tostring
    public static void main01(String[] args) {
    	Person person = new Person();
    	person.setId("001");
    	person.setName("002");
    	System.out.println(toString(person));
    	 
	}
    //测试基类
   static class Person {
    	
    	
    	private String id;
    	private String name ;
		public String getId() {
			return id;
		}
		public void setId(String id) {
			this.id = id;
		}
		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
    	
    	
    }
    /**
     * 把String类型转换成map(只需键值对)
     * 
     * @param stringByMap 键值对的形式,中间用英文逗号分隔
     * @return map
     */
    public static Map refertForMap(String stringByMap) {
        // 验证输入,若是空,返回null
      /*  if (Validate.isNull(stringByMap)) {
            return null;
        }*/
        // 根据“,”分隔开每一组数值
        String[] keyValues = stringByMap.split(",");
        // 定义返回类型
        Map map = new HashMap();
        for (int i = 0; i < keyValues.length; i++) {
            // 根据“=”分隔开key和value值
            // 存放每一组数值
            String[] key_value = keyValues[i].split("=");
            // 如果不存在key或value则继续下次组装
            if (key_value.length != 2) {	
                continue;
            }
            // 存放key和value
            //网站认证中心
            String key;
            // 把key值去除空格,并转成大写
            try {
                key = key_value[0].trim().toUpperCase();
            } catch (RuntimeException e) {
                continue;
            }
            // 获取value值
            String value = key_value[1];
            // 存入map
            map.put(key, value);
        }
        // 返回map
        return map;
    }
    //测试
    public static void main02(String[] args) {
    	String string = "id=1,name=2";
    	Map<String, Object> map =refertForMap(string);
     for(String key:map.keySet()){
    	 
    	 System.out.println(key+"="+map.get(key));
     }
    
    }
    /**
     * 把String类型转换成对象
     * 
     * @param stringByObject 键值对的形式,中间用英文逗号分隔
     * @param obj            要映射的对象
     * @return Object 映射后的对象
     * @throws Exception
     */
    public static Object refertForObject(String stringByObject, Object obj) {
        if ("java.lang.Class".equals(obj.getClass().getName())) {
            System.out.println("Object不应为java.lang.Class类型");
        }
        // 验证输入,若是空,返回null
      /*  if (Validate.isNull(stringByObject)) {
            return null;
        }*/
        // 根据“,”分隔开每一组数值
        String[] keyValues = stringByObject.split(",");
        // 存放key和value
        String key, value;
        // 定义返回类型
        for (int i = 0; i < keyValues.length; i++) {
            // 根据“=”分隔开key和value值
            // 存放每一组数值
            String[] key_value = keyValues[i].split("=");
            // 如果不存在key或value则继续下次组装
            if (key_value.length != 2) {
                continue;
            }
            // 把key值去除空格,并转成大写
            try {
                key = key_value[0].trim().toUpperCase();
            } catch (RuntimeException e) {
                continue;
            }
            // 获取value值
            value = key_value[1];
            // 存入map
            setObject(key, value, obj);
        }
        // 返回map
        return obj;
    }

    //
    public static void main(String[] args) {
    	String string = "id=1,name=2";
    	Person person = new Person();
    	person =(Person)refertForObject(string,person);
    	System.out.println(person.getId());
    	System.out.println(person.getName());
	}
    /**
     * 把request映射成map
     * 
     * @param request
     * @return
     * @throws RefertException
     */
    public static Map refertForMapByRequest(HttpServletRequest request)  {
    	  // 存放符合条件的name-value映射值  
    	Map initMap = new HashMap();
    	try {
            // 获取页面上的所有name值
            Enumeration pNames = request.getParameterNames();
          
         
            // 获取页面的操作类型
            // 遍历页面所有的name值
            while (pNames.hasMoreElements()) {
                // 获取当前要验证的name值
                String name = (String) pNames.nextElement();
                String value = request.getParameter(name);
                initMap.put(name.toUpperCase(), value);
            }
            // 返回map
            return initMap;
        } catch (Exception e) {
        	System.out.println("获取页面信息失败\n" + e);
        	 return initMap;
        }
    }

    /**
     * 把request映射成Object
     * 
     * @param request
     * @param obj
     * @return
     * @throws RefertException
     */
    public static Object refertForObjectByRequest(HttpServletRequest request, Object obj) {
        try {
            Map map = refertForMapByRequest(request);
            refertForObjectByMap(map, obj);
            return obj;
        } catch (Exception e) {
        	System.out.println(e);
        	 return obj;
        }
    }

    /**
     * 把Object映射成Map
     * 
     * @param object
     * @return
     * @throws RefertException
     */
    public static Map<String, Object> refertForMapByObject(Object object)  {
        if (object == null) {
            return null;
        }
        Map<String, Object> map = new HashMap<String, Object>();
        Class c = object.getClass();
        Method[] methods = c.getMethods();
        Field[] fields = c.getDeclaredFields();
        String fieldName, methodName;
        Method method;
        Field field;
        for (int i = 0; i < fields.length; i++) {
            field = fields[i];
            fieldName = field.getName();
            for (int j = 0; j < methods.length; j++) {
                method = methods[j];
                methodName = method.getName();
                if (methodName.toUpperCase().endsWith("GET" + fieldName.toUpperCase())) {
                    try {
                        map.put(fieldName, method.invoke(object));
                    } catch (Exception e) {
                    	System.out.println("映射新对象" + c + "失败,列名:" + fieldName + ",方法名:" + methodName + "/n" + e);
                    }
                    break;
                }
            }
        }
        return map;
    }

    /**
     * 把map映射成对象
     * 
     * @param map 映射源内容
     * @param obj 映射成的对象
     * @return obj
     * @throws RefertException
     */
    public static Object refertForObjectByMap(Map<Object, Object> map, Object obj)  {
        try {
        	//验证
           /* if (Validate.isNull(map))
                return null;
            if (Validate.isNull(obj))
                return null;*/
            if ("java.lang.Class".equals(obj.getClass().getName()))
            	System.out.println("Object不应为java.lang.Class类型");
            for (Map.Entry<Object, Object> e : map.entrySet()) {
                String key = e.getKey().toString();
                Object value = e.getValue();
                setObject(key, value, obj);
            }
            return obj;
        } catch (Exception e) {
        	System.out.println(e);
        	 return obj;
        }
    }

    /**
     * 映射对象
     * 
     * @param name  映射的名称
     * @param value 映射的值
     * @param obj   映射的对象
     * @return 映射完成的对象
     * @throws RefertException
     */
    private static Object setObject(String name, Object value, Object obj) {
        Class c = obj.getClass();
        String setName;
        name = "SET" + name;
        name = name.toUpperCase();
        Method[] methods = c.getDeclaredMethods();
        Method method;
        String valueType = value.getClass().getName();
        for (int i = 0; i < methods.length; i++) {
            method = methods[i];
            setName = method.getName().toUpperCase();
            if (name.equals(setName)) {
                Class[] pts = method.getParameterTypes();
                if (pts.length != 1) {
                	System.out.println("映射新对象" + c + "失败,name=" + name + "的传入参数不唯一,映射失败\n");
                }
                String parameterType = pts[0].getTypeName();
                if (parameterType.equals(valueType)) {
                    // 对象接收值类型与传入值类型相同
                } else if ("java.util.Map".equals(parameterType) && Map.class.isAssignableFrom(value.getClass())) {
                    // 对象接收值类型map是传入值的父类
                } else if ("java.util.List".equals(parameterType) && List.class.isAssignableFrom(value.getClass())) {
                    // 对象接收值类型list是传入值的父类
                } else if ("java.lang.Object".equals(parameterType)) {
                    // 对象接收值类型object
                } else if ("java.lang.String".equals(value.getClass().getName())) {
                    try {
                        if ("byte".equals(parameterType)) {
                            value = Byte.valueOf((String) value);
                        } else if ("short".equals(parameterType)) {
                            value = Short.valueOf((String) value);
                        } else if ("int".equals(parameterType)) {
                            value = Integer.valueOf((String) value);
                        } else if ("long".equals(parameterType)) {
                            value = Long.valueOf((String) value);
                        } else if ("float".equals(parameterType)) {
                            value = Float.valueOf((String) value);
                        } else if ("double".equals(parameterType)) {
                            value = Double.valueOf((String) value);
                        } else if ("char[]".equals(parameterType)) {
                            value = value.toString().toCharArray();
                        } else if ("boolean".equals(parameterType)) {
                            value = Boolean.valueOf((String) value);
                        } else if ("double".equals(parameterType)) {
                            value = Double.valueOf((String) value);
                        } else {
                            // map不支持(map内嵌套map,对map根据逗号进行拆分时出错)
                        	System.out.println();
                        }
                    } catch (Exception e) {
                        StringBuffer refertLogger = new StringBuffer();
                        refertLogger.append("映射新对象" + c + "失败,");
                        refertLogger.append("name=" + name + ",");
                        refertLogger.append(valueType + "强转为" + parameterType + "失败");
                        System.out.println(refertLogger.toString());
                    }
                } else {
                    StringBuffer refertLogger = new StringBuffer();
                    refertLogger.append("映射新对象" + c + "失败,");
                    refertLogger.append("name=" + name + ",");
                    refertLogger.append(valueType + "强转为" + parameterType + "失败");
                    System.out.println(refertLogger.toString());
                }
                try {
                    method.invoke(obj, value);
                    break;
                } catch (Exception e) {
                    StringBuffer refertLogger = new StringBuffer();
                    refertLogger.append("映射新对象" + c + "失败,");
                    refertLogger.append("name=" + name + "。");
                    System.out.println(refertLogger.toString());
                }
            }
        }
        return obj;
    }

}

相关标签: java数据转换