以下是我使用 Java Reflection API 构建的解决方案的说明。我已经在下面发布了工作代码（及其到 github 的 url）。本方案主要使用：
- Java 反射 API
- Java 集合的独立处理
- 递归
首先，我使用Introspector 遍历Class 的readMethods，省略了为Object 定义的方法
for (PropertyDescriptor propertyDescriptor : Introspector
.getBeanInfo(c, Object.class).getPropertyDescriptors()) {
Method method = propertyDescriptor.getReadMethod();
案例
- 如果
Property 的当前级别是String 类型
- 如果它是
Object 属性数组
- 如果是
String 数组
- 如果它是一种 Java
Collection 类
- 单独放置
Map 并使用特殊条件处理其 键 和 值
此实用程序使用 Java 反射 API 遍历具有 getters 和 setters 规范语法的对象图，并以递归方式修剪 Object 图中遇到的所有字符串。
代码
这个带有主要测试类（和自定义数据类型/pojos）的整个 util 类是here on my github
用法：
myObj = (MyObject) SpaceUtil.trimReflective(myObj);
使用方法：
public static Object trimReflective(Object object) throws Exception {
if (object == null)
return null;
Class<? extends Object> c = object.getClass();
try {
// Introspector usage to pick the getters conveniently thereby
// excluding the Object getters
for (PropertyDescriptor propertyDescriptor : Introspector
.getBeanInfo(c, Object.class).getPropertyDescriptors()) {
Method method = propertyDescriptor.getReadMethod();
String name = method.getName();
// If the current level of Property is of type String
if (method.getReturnType().equals(String.class)) {
String property = (String) method.invoke(object);
if (property != null) {
Method setter = c.getMethod("set" + name.substring(3),
new Class<?>[] { String.class });
if (setter != null)
// Setter to trim and set the trimmed String value
setter.invoke(object, property.trim());
}
}
// If an Object Array of Properties - added additional check to
// avoid getBytes returning a byte[] and process
if (method.getReturnType().isArray()
&& !method.getReturnType().isPrimitive()
&& !method.getReturnType().equals(String[].class)
&& !method.getReturnType().equals(byte[].class)) {
System.out.println(method.getReturnType());
// Type check for primitive arrays (would fail typecasting
// in case of int[], char[] etc)
if (method.invoke(object) instanceof Object[]) {
Object[] objectArray = (Object[]) method.invoke(object);
if (objectArray != null) {
for (Object obj : (Object[]) objectArray) {
// Recursively revisit with the current property
trimReflective(obj);
}
}
}
}
// If a String array
if (method.getReturnType().equals(String[].class)) {
String[] propertyArray = (String[]) method.invoke(object);
if (propertyArray != null) {
Method setter = c.getMethod("set" + name.substring(3),
new Class<?>[] { String[].class });
if (setter != null) {
String[] modifiedArray = new String[propertyArray.length];
for (int i = 0; i < propertyArray.length; i++)
if (propertyArray[i] != null)
modifiedArray[i] = propertyArray[i].trim();
// Explicit wrapping
setter.invoke(object,
new Object[] { modifiedArray });
}
}
}
// Collections start
if (Collection.class.isAssignableFrom(method.getReturnType())) {
Collection collectionProperty = (Collection) method
.invoke(object);
if (collectionProperty != null) {
for (int index = 0; index < collectionProperty.size(); index++) {
if (collectionProperty.toArray()[index] instanceof String) {
String element = (String) collectionProperty
.toArray()[index];
if (element != null) {
// Check if List was created with
// Arrays.asList (non-resizable Array)
if (collectionProperty instanceof List) {
((List) collectionProperty).set(index,
element.trim());
} else {
collectionProperty.remove(element);
collectionProperty.add(element.trim());
}
}
} else {
// Recursively revisit with the current property
trimReflective(collectionProperty.toArray()[index]);
}
}
}
}
// Separate placement for Map with special conditions to process
// keys and values
if (method.getReturnType().equals(Map.class)) {
Map mapProperty = (Map) method.invoke(object);
if (mapProperty != null) {
// Keys
for (int index = 0; index < mapProperty.keySet().size(); index++) {
if (mapProperty.keySet().toArray()[index] instanceof String) {
String element = (String) mapProperty.keySet()
.toArray()[index];
if (element != null) {
mapProperty.put(element.trim(),
mapProperty.get(element));
mapProperty.remove(element);
}
} else {
// Recursively revisit with the current property
trimReflective(mapProperty.get(index));
}
}
// Values
for (Map.Entry entry : (Set<Map.Entry>) mapProperty
.entrySet()) {
if (entry.getValue() instanceof String) {
String element = (String) entry.getValue();
if (element != null) {
entry.setValue(element.trim());
}
} else {
// Recursively revisit with the current property
trimReflective(entry.getValue());
}
}
}
} else {// Catch a custom data type as property and send through
// recursion
Object property = (Object) method.invoke(object);
if (property != null) {
trimReflective(property);
}
}
}
} catch (Exception e) {
throw new Exception("Strings cannot be trimmed because: ", e);
}
return object;
}
测试
我还有一个测试类，它创建了一个相对复杂的对象。测试类有不同的场景，涵盖：
-
String属性
- 作为自定义数据类型的属性又具有
String 属性
- 作为自定义数据类型的属性又具有作为自定义数据类型的属性，而自定义数据类型又具有
String 属性
-
List 的自定义数据类型
-
Set 的 Strings
-
Array 的自定义数据类型
-
Array 的 Strings
-
Map of String 和自定义数据类型
对象图：
测试对象代码片段：
public static Music buildObj() {
Song song1 = new Song();
Song song2 = new Song();
Song song3 = new Song();
Artist artist1 = new Artist();
Artist artist2 = new Artist();
song1.setGenre("ROCK ");
song1.setSonnet("X ");
song1.setNotes("Y ");
song1.setCompostions(Arrays.asList(new String[] { "SOME X DATA ",
"SOME OTHER DATA X ", "SOME MORE DATA X ", " " }));
Set<String> instruments = new HashSet<String>();
instruments.add(" GUITAR ");
instruments.add(" SITAR ");
instruments.add(" DRUMS ");
instruments.add(" BASS ");
song1.setInstruments(instruments);
song2.setGenre("METAL ");
song2.setSonnet("A ");
song2.setNotes("B ");
song2.setCompostions(Arrays.asList(new String[] { "SOME Y DATA ",
" SOME OTHER DATA Y ",
" SOME MORE DATA Y ", " " }));
song3.setGenre("POP ");
song3.setSonnet("DONT ");
song3.setNotes("KNOW ");
song3.setCompostions(Arrays.asList(new String[] { "SOME Z DATA ",
" SOME OTHER DATA Z ",
" SOME MORE DATA Z ", " " }));
artist1.setSongList(Arrays.asList(new Song[] { song1, song3 }));
artist2.setSongList(Arrays.asList(new Song[] { song1, song2, song3 }));
Map<String, Person> artistMap = new HashMap<String, Person>();
Person tutor1 = new Person();
tutor1.setName("JOHN JACKSON DOE ");
artistMap.put(" Name ", tutor1);
Person coach1 = new Person();
coach1.setName("CARTER ");
artistMap.put("Coach ", coach1);
artist2.setTutor(artistMap);
music.setSongs(Arrays.asList(new Song[] { song1, song2, song3 }));
music.setArtists(Arrays.asList(new Artist[] { artist1, artist2 }));
music.setLanguages(new String[] { " ENGLISH ", "FRENCH ",
"HINDI " });
Person singer1 = new Person();
singer1.setName("DAVID ");
Person singer2 = new Person();
singer2.setName("JACOB ");
music.setSingers(new Person[] { singer1, singer2 });
Human man = new Human();
Person p = new Person();
p.setName(" JACK'S RAGING BULL ");
SomeGuy m = new SomeGuy();
m.setPerson(p);
man.setMan(m);
music.setHuman(man);
return music;
}
结果：
#######BEFORE#######
>>[>>DAVID ---<<, >>JACOB ---<<]---[ ENGLISH , FRENCH , HINDI ]---[>>ROCK ---X ---Y ---[SOME X DATA , SOME OTHER DATA X , SOME MORE DATA X , ]---[ SITAR , GUITAR , BASS , DRUMS ]<<, >>METAL ---A ---B ---[SOME Y DATA , SOME OTHER DATA Y , SOME MORE DATA Y , ]---<<, >>POP ---DONT ---KNOW ---[SOME Z DATA , SOME OTHER DATA Z , SOME MORE DATA Z , ]---<<]---[>>---[>>ROCK ---X ---Y ---[SOME X DATA , SOME OTHER DATA X , SOME MORE DATA X , ]---[ SITAR , GUITAR , BASS , DRUMS ]<<, >>POP ---DONT ---KNOW ---[SOME Z DATA , SOME OTHER DATA Z , SOME MORE DATA Z , ]---<<]<<, >>{Coach =>>CARTER ---<<, Name =>>JOHN JACKSON DOE ---<<}---[>>ROCK ---X ---Y ---[SOME X DATA , SOME OTHER DATA X , SOME MORE DATA X , ]---[ SITAR , GUITAR , BASS , DRUMS ]<<, >>METAL ---A ---B ---[SOME Y DATA , SOME OTHER DATA Y , SOME MORE DATA Y , ]---<<, >>POP ---DONT ---KNOW ---[SOME Z DATA , SOME OTHER DATA Z , SOME MORE DATA Z , ]---<<]<<]---=> JACK'S RAGING BULL <=<<
Number of spaces : 644
#######AFTER#######
>>[>>DAVID---<<, >>JACOB---<<]---[ENGLISH, FRENCH, HINDI]---[>>ROCK---X---Y---[SOME X DATA, SOME OTHER DATA X, SOME MORE DATA X, ]---[GUITAR, SITAR, DRUMS, BASS]<<, >>METAL---A---B---[SOME Y DATA, SOME OTHER DATA Y, SOME MORE DATA Y, ]---<<, >>POP---DONT---KNOW---[SOME Z DATA, SOME OTHER DATA Z, SOME MORE DATA Z, ]---<<]---[>>---[>>ROCK---X---Y---[SOME X DATA, SOME OTHER DATA X, SOME MORE DATA X, ]---[GUITAR, SITAR, DRUMS, BASS]<<, >>POP---DONT---KNOW---[SOME Z DATA, SOME OTHER DATA Z, SOME MORE DATA Z, ]---<<]<<, >>{Name=>>JOHN JACKSON DOE---<<, Coach=>>CARTER---<<}---[>>ROCK---X---Y---[SOME X DATA, SOME OTHER DATA X, SOME MORE DATA X, ]---[GUITAR, SITAR, DRUMS, BASS]<<, >>METAL---A---B---[SOME Y DATA, SOME OTHER DATA Y, SOME MORE DATA Y, ]---<<, >>POP---DONT---KNOW---[SOME Z DATA, SOME OTHER DATA Z, SOME MORE DATA Z, ]---<<]<<]---=>JACK'S RAGING BULL<=<<
Number of spaces : 111
上述修剪输出中的空格数计数非零，因为我没有努力覆盖任何集合的toString（List、@987654353 @) 或Map。我想要对代码进行某些改进，但对于您的情况，解决方案应该可以正常工作。
限制（进一步改进）
- 无法处理不规范的属性语法（无效的 getter/setter）
- 无法处理链式集合：例如，
List<List<Person>> - 因为独家支持严格的 getter/setter 约定
- 不支持 Guava 集合库