看朋友写数据库查询，获取结果的时候，每次都会写一大堆代码，我想起以前Java里写过一个公用的方法。
因为初学Android所以就试着写一个，可以满足我的需求。
有什么需要改的或者优化的还请赐教。
代码如下：

1. package cn.com.choicesoft.weiqian.util;
   
2. 
   
3. import java.lang.reflect.Method;
   
4. import java.util.ArrayList;
   
5. import java.util.List;
   
6. 
   
7. import <a title="android" href="http://www.android-study.com/jichuzhishi/567.html">android</a>.content.Context;
   
8. import <a title="android" href="http://www.android-study.com/jichuzhishi/567.html">android</a>.database.Cursor;
   
9. import <a title="android" href="http://www.android-study.com/jichuzhishi/567.html">android</a>.database.<a title="sqlite" href="http://www.android-study.com/jichuzhishi/567.html">sqlite</a>.SQLiteDatabase;
   
10. 
    
11. /**
    
12. *@Author:M.c
    
13. *@Comments:数据库公用查询结果 处理类
    
14. *@CreateDate:2014-1-20
    
15. *@Email:JNWSCZH@163.COM
    
16. */
    
17. public class ListProcessor {
    
18. private DBManager db;
    
19. public DBManager getDb(Context context) {
    
20. if(db==null){
    
21. db = new DBManager(context);
    
22. }
    
23. return db;
    
24. }
    
25. /**
    
26. * 根据传入实体返回对应的实体数组
    
27. * @param sql SQL语句
    
28. * @param selectionArgs SQL条件
    
29. * @param context Activity
    
30. * @param cal 实体类 【实体内属性只支持：String,Integer,Float,Double,Boolean,Short,Long,Character(char)】
    
31. * @return List<T>
    
32. */
    
33. public <T> List<T> query(String sql,String[] selectionArgs,Context context,Class<T> cal){
    
34. SQLiteDatabase database = getDb(context).openDatabase();
    
35. Cursor c = database.rawQuery(sql, selectionArgs);
    
36. Method[] methods = cal.getMethods();
    
37. List<T> list=new ArrayList<T>();
    
38. while (c.moveToNext()) {
    
39. Object obj=null;
    
40. try {
    
41. obj=cal.newInstance();
    
42. } catch (InstantiationException e) {
    
43. e.printStackTrace();
    
44. } catch (IllegalAccessException e) {
    
45. e.printStackTrace();
    
46. }
    
47. for (Method method : methods) {
    
48. String methodName=method.getName();
    
49. if(methodName.matches("^set[A-Z]\w+$")){
    
50. String name=methodName.substring(3, methodName.length()).toUpperCase();
    
51. for (int i=0;i<c.getColumnCount();i++) {
    
52. if(name.equalsIgnoreCase(c.getColumnName(i))){
    
53. try {
    
54. typeDivision(method,c.getString(i),cal,obj);
    
55. break;
    
56. } catch (Exception e) {
    
57. e.printStackTrace();
    
58. }
    
59. }
    
60. }
    
61. }
    
62. }
    
63. list.add((T)obj);
    
64. }
    
65. if(c!=null){
    
66. c.close();
    
67. }
    
68. if(database!=null){
    
69. database.close();
    
70. }
    
71. return list;
    
72. }
    
73. /**
    
74. * 不同类型转换
    
75. * @param method
    
76. * @param value
    
77. * @param cla
    
78. * @throws Exception
    
79. */
    
80. public void typeDivision(Method method, Object value, Class<?> cls,Object obj) throws Exception {
    
81. Object typeName = method.getParameterTypes()[0];
    
82. Method setMethod = null;
    
83. if (typeName == String.class) {
    
84. setMethod = cls.getMethod(method.getName(), String.class);
    
85. setMethod.invoke(obj, value.toString());
    
86. }else if (typeName == Double.class||typeName.toString().equals("double")){
    
87. setMethod = cls.getMethod(method.getName(), typeName == Double.class?Double.class:double.class);
    
88. setMethod.invoke(obj, new Double(value.toString()));
    
89. }else if (typeName == Integer.class||typeName.toString().equals("int")) {
    
90. setMethod = cls.getMethod(method.getName(), typeName == Integer.class?Integer.class:int.class);
    
91. setMethod.invoke(obj, Integer.valueOf(value.toString()));
    
92. }else if (typeName == Long.class||typeName.toString().equals("long")) {
    
93. setMethod = cls.getMethod(method.getName(), typeName == Long.class?Long.class:long.class);
    
94. setMethod.invoke(obj, Long.valueOf(value.toString()));
    
95. } else if (typeName == Character.class||typeName.toString().equals("char")) {
    
96. setMethod = cls.getMethod(method.getName(),typeName == Character.class?Character.class:char.class);
    
97. setMethod.invoke(obj, value.toString().charAt(0));
    
98. } else if (typeName == Boolean.class||typeName.toString().equals("boolean")) {
    
99. setMethod = cls.getMethod(method.getName(), typeName == Boolean.class?Boolean.class:boolean.class);
    
100. setMethod.invoke(obj, new Boolean(value.toString()));
     
101. } else if (typeName == Float.class||typeName.toString().equals("float")) {
     
102. setMethod = cls.getMethod(method.getName(), typeName == Float.class?Float.class:float.class);
     
103. setMethod.invoke(obj, Float.valueOf(value.toString()));
     
104. } else if (typeName == Short.class||typeName.toString().equals("short")) {
     
105. setMethod = cls.getMethod(method.getName(), typeName == Short.class?Short.class:short.class);
     
106. setMethod.invoke(obj, Short.valueOf(value.toString()));
     
107. }
     
108. }
     
109. }

复制代码

顶一个。。