|
1 |
| -# Expression说明文档 |
2 |
| - |
3 |
| -## 1. 概述 |
4 |
| - |
5 |
| -用于方便的从对象、数组、Map等结构中获取值 |
6 |
| - |
7 |
| -### 1.1. 引用 |
8 |
| - |
9 |
| -```xml |
10 |
| -<dependency> |
11 |
| - <groupId>com.github.developframework</groupId> |
12 |
| - <artifactId>expression</artifactId> |
13 |
| - <version>${version.expression}</version> |
14 |
| -</dependency> |
15 |
| -``` |
16 |
| - |
17 |
| -### 1.2. 依赖项 |
18 |
| - |
19 |
| -- commons-lang3.jar |
20 |
| -- slf4j-api.jar |
21 |
| -- lombok.jar |
22 |
| - |
23 |
| -## 2. 简单示例 |
24 |
| - |
25 |
| -### 2.1. 表达式对象 |
26 |
| -```java |
27 |
| -Expression expression = Expression.parse("user.name"); |
28 |
| -``` |
29 |
| - |
30 |
| -把字符串`user.name` 解析成一个表达式对象。 |
31 |
| - |
32 |
| -可以解析的表达式字符串有: |
33 |
| - |
34 |
| -| 表达式字符串 | 描述 | |
35 |
| -| ------------- | ---------------------------------------- | |
36 |
| -| user.name | 从根对象(根对象是对象或Map)取得user实例的name属性 | |
37 |
| -| users[0].name | 从根对象(根对象是对象或Map)取得users数组实例的第1个元素的name属性 | |
38 |
| -| [0].name | 从根对象(根对象是数组)取得第1个元素的name属性 | |
39 |
| - |
40 |
| -### 2.2. 取值 |
41 |
| - |
42 |
| -例如有如下结构的User实体类: |
43 |
| - |
44 |
| -```java |
45 |
| -@Data |
46 |
| -public class User { |
47 |
| - |
48 |
| - private String name; |
49 |
| - |
50 |
| - private String[] emails; |
51 |
| - |
52 |
| - public User(String name, String[] emails) { |
53 |
| - this.name = name; |
54 |
| - this.emails = emails; |
55 |
| - } |
56 |
| -} |
57 |
| -``` |
58 |
| - |
59 |
| -有如下的数据结构关系: |
60 |
| - |
61 |
| -```java |
62 |
| -User peter = new User("Peter", new String[]{"peter@163.com", "peter@qq.com"}); |
63 |
| -User tom = new User("Tom", new String[]{"tom@163.com", "tom@qq.com"}); |
64 |
| -User[] users = new User[]{peter, tom}; |
65 |
| -Map<String, Object> map = new HashMap<>(); |
66 |
| -map.put("users", users); |
67 |
| -``` |
68 |
| - |
69 |
| -说明:peter,tom两个User对象存放于users数组对象中,而users数组对象存放于map中,键值为"users"。 |
70 |
| - |
71 |
| -那么假如要从map中取得peter的第二个email值。普通java代码如下: |
72 |
| - |
73 |
| -```java |
74 |
| -String peterSecondEmail = ((User[])map.get("users"))[0].getMails()[1]; |
75 |
| -``` |
76 |
| - |
77 |
| -列为表达式:`users[0].emails[1]` |
78 |
| - |
79 |
| -```java |
80 |
| -String expressionValue = "users[0].emails[1]"; |
81 |
| -String peterSecondEmail = ExpressionUtils.getValue(map, expressionValue, String.class); |
82 |
| -System.out.println(peterSecondEmail); |
83 |
| -``` |
84 |
| - |
| 1 | +# Expression说明文档 |
| 2 | + |
| 3 | +## 1. 概述 |
| 4 | + |
| 5 | +用于方便的从对象、数组、Map等结构中获取值 |
| 6 | + |
| 7 | +### 1.1. 引用 |
| 8 | + |
| 9 | +```xml |
| 10 | +<dependency> |
| 11 | + <groupId>com.github.developframework</groupId> |
| 12 | + <artifactId>expression</artifactId> |
| 13 | + <version>${version.expression}</version> |
| 14 | +</dependency> |
| 15 | +``` |
| 16 | + |
| 17 | +### 1.2. 依赖项 |
| 18 | + |
| 19 | +- commons-lang3.jar |
| 20 | +- slf4j-api.jar |
| 21 | +- lombok.jar |
| 22 | + |
| 23 | +## 2. 简单示例 |
| 24 | + |
| 25 | +### 2.1. 表达式对象 |
| 26 | +```java |
| 27 | +Expression expression = Expression.parse("user.name"); |
| 28 | +``` |
| 29 | + |
| 30 | +把字符串`user.name` 解析成一个表达式对象。 |
| 31 | + |
| 32 | +可以解析的表达式字符串有: |
| 33 | + |
| 34 | +| 表达式字符串 | 描述 | |
| 35 | +| ------------- | ---------------------------------------- | |
| 36 | +| user.name | 从根对象(根对象是对象或Map)取得user实例的name属性 | |
| 37 | +| users[0].name | 从根对象(根对象是对象或Map)取得users数组实例的第1个元素的name属性 | |
| 38 | +| [0].name | 从根对象(根对象是数组)取得第1个元素的name属性 | |
| 39 | + |
| 40 | +### 2.2. 取值 |
| 41 | + |
| 42 | +例如有如下结构的User实体类: |
| 43 | + |
| 44 | +```java |
| 45 | +@Data |
| 46 | +public class User { |
| 47 | + |
| 48 | + private String name; |
| 49 | + |
| 50 | + private String[] emails; |
| 51 | + |
| 52 | + public User(String name, String[] emails) { |
| 53 | + this.name = name; |
| 54 | + this.emails = emails; |
| 55 | + } |
| 56 | +} |
| 57 | +``` |
| 58 | + |
| 59 | +有如下的数据结构关系: |
| 60 | + |
| 61 | +```java |
| 62 | +User peter = new User("Peter", new String[]{"peter@163.com", "peter@qq.com"}); |
| 63 | +User tom = new User("Tom", new String[]{"tom@163.com", "tom@qq.com"}); |
| 64 | +User[] users = new User[]{peter, tom}; |
| 65 | +Map<String, Object> map = new HashMap<>(); |
| 66 | +map.put("users", users); |
| 67 | +``` |
| 68 | + |
| 69 | +说明:peter,tom两个User对象存放于users数组对象中,而users数组对象存放于map中,键值为"users"。 |
| 70 | + |
| 71 | +那么假如要从map中取得peter的第二个email值。普通java代码如下: |
| 72 | + |
| 73 | +```java |
| 74 | +String peterSecondEmail = ((User[])map.get("users"))[0].getMails()[1]; |
| 75 | +``` |
| 76 | + |
| 77 | +列为表达式:`users[0].emails[1]` |
| 78 | + |
| 79 | +```java |
| 80 | +String expressionValue = "users[0].emails[1]"; |
| 81 | +String peterSecondEmail = ExpressionUtils.getValue(map, expressionValue, String.class); |
| 82 | +System.out.println(peterSecondEmail); |
| 83 | +``` |
| 84 | + |
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