用java的反射实现将ResultSet自动转化成对象,自动产生sql语句

转自： http://blog.csdn.net/hanghangde/article/details/53946722  

主要就是ResultSetToData和TranesformToSql文件的代码: 
ResultSetToData.java

package com.lirui.order.dao.tool;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;public class ResultSetToData {    /**     * 根据clazz和ResultSet返回对象(这个对象里的全部属性)集合     *      * @param rs     * @param clazz     * @return     */    public static <T> ArrayList<T> getDataByClassFiled(ResultSet rs,            Class<T> clazz) {        ArrayList<T> domains = new ArrayList<>();        try {            // 获得自己的属性            Field[] fields = clazz.getDeclaredFields();            // 获得父类的属性            Field[] superFields = clazz.getSuperclass().getDeclaredFields();            // 自己的和父类的属性相加            Field[] allFields = addFields(fields, superFields);            while (rs.next()) {                T vo = clazz.newInstance();                // 历遍所有的属性                for (Field field : allFields) {                    String methodName = getSetterMethodName(field.getName());                    Method method = clazz                            .getMethod(methodName, field.getType());                    invokeMothod(rs, field, method, vo);                }                domains.add(vo);            }        } catch (InstantiationException | IllegalAccessException                | SecurityException | SQLException | NoSuchMethodException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return domains;    }    /**     * 根据返回的resultSet来决定生成对象有那些属性     *      * @param rs     * @param clazz     * @return     */    public static <T> ArrayList<T> getDataByResultSet(ResultSet rs,            Class<T> clazz) {        ArrayList<T> domains = new ArrayList<>();        // 通过metaData获取到的属性生成对应的FieldList        List<Field> allFields = new ArrayList<>();        try {            //如果未空值返回            if (null==rs) {                return null;            }            // 先获取元数据再通过元数据进行细化的操作            java.sql.ResultSetMetaData metaData = rs.getMetaData();            // 通过ResultSet里面的column的名字来决定用这个类的哪一个Field            for (int i = 0; i < metaData.getColumnCount(); i++) {                allFields                        .add(clazz.getDeclaredField(metaData.getColumnName(i+1)));                // allFields.add(clazz.getSuperclass().getDeclaredField(                // metaData.getColumnName(i+1)));            }            while (rs.next()) {                T vo = clazz.newInstance();                // 历遍所有的属性                for (Field field : allFields) {                    String methodName = getSetterMethodName(field.getName());                    Method method = clazz                            .getMethod(methodName, field.getType());                    invokeMothod(rs, field, method, vo);                }                domains.add(vo);            }        } catch (InstantiationException | IllegalAccessException                | SecurityException | SQLException | NoSuchMethodException                | NoSuchFieldException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return domains;    }    /**     * 相加f1和f2的Field     *      * @param f1     * @param f2     * @return     */    private static Field[] addFields(Field[] f1, Field[] f2) {        List<Field> fields = new ArrayList<>();        for (Field field : f1) {            fields.add(field);        }        for (Field field : f2) {            fields.add(field);        }        return fields.toArray(new Field[f1.length + f2.length]);    }    /**     * 根据属性名得到set的方法名     *      * @param name     * @return     */    private static String getSetterMethodName(String name) {        String begin = name.substring(0, 1).toUpperCase();        String mothodName = "set" + begin + name.substring(1, name.length());        return mothodName;    }    /**     * 根据ResultSet和Field的getName从结果集取出     *      * @param rs     * @param field     * @param method     * @param object     */    private static void invokeMothod(ResultSet rs, Field field, Method method,            Object object) {        try {            Object o=rs.getObject(field.getName());            method.invoke(object, o);        } catch (IllegalAccessException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IllegalArgumentException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (InvocationTargetException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158

TansformToSql.java

package com.lirui.order.dao.tool;import java.lang.reflect.Field;public class TransformToSql {    /**     * 通过反射机制生成插入sql语句     *      * @param clazz     * @return     */    public static String transformToInsertSql(Class<?> clazz) {        StringBuffer bufferFront = new StringBuffer();        StringBuffer bufferLast = new StringBuffer();        String tableName = clazz.getSimpleName();        bufferFront.append("insert into "                + tableName.substring(0, 1).toLowerCase()                + tableName.substring(1, tableName.length()) + "(");        bufferLast.append(" values(");        // 通过class得到所有的属性不受访问控制符空值        Field[] fields = clazz.getDeclaredFields();        for (Field field : fields) {            bufferFront.append(field.getName() + ",");            bufferLast.append("?,");        }        bufferFront.delete(bufferFront.length() - 1, bufferFront.length());        bufferLast.delete(bufferLast.length() - 1, bufferLast.length());        bufferFront.append(")");        bufferLast.append(")");        bufferFront.append(bufferLast);        return bufferFront.toString();    }    /**     * 通过反射机制生成通用的更新语句     *      * @param clazz     * @return     */    public static String transformToUpdateSql(Class<?> clazz) {        StringBuffer bufferFront = new StringBuffer();        StringBuffer bufferLast = new StringBuffer();        String tableName = clazz.getSimpleName();        bufferFront.append("update " + tableName.substring(0, 1).toLowerCase()                + tableName.substring(1, tableName.length()) + " set ");        bufferLast.append(" where id=?");        // 通过class得到所有的属性不受访问控制符空值        Field[] fields = clazz.getDeclaredFields();        for (Field field : fields) {            if (field.getName().equals("id"))                continue;            bufferFront.append(field.getName() + "=?,");        }        bufferFront.delete(bufferFront.length() - 1, bufferFront.length());        bufferFront.append(bufferLast);        return bufferFront.toString();    }}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62