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cn.hutool.core.bean.BeanPath Maven / Gradle / Ivy
package cn.hutool.core.bean;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.convert.Convert;
import cn.hutool.core.map.MapUtil;
import cn.hutool.core.text.StrBuilder;
import cn.hutool.core.util.ArrayUtil;
import cn.hutool.core.util.CharUtil;
import cn.hutool.core.util.StrUtil;
/**
* Bean路径表达式，用于获取多层嵌套Bean中的字段值或Bean对象
* .表达式，可以获取Bean对象中的属性（字段）值或者Map中key对应的值
* []表达式，可以获取集合等对象中对应index的值
*
*
* 表达式栗子：
*
*
* persion
* persion.name
* persons[3]
* person.friends[5].name
* ['person']['friends'][5]['name']
*
*
* @author Looly
* @since 4.0.6
*/
public class BeanPath implements Serializable{
private static final long serialVersionUID = 1L;
/** 表达式边界符号数组 */
private static final char[] expChars = { CharUtil.DOT, CharUtil.BRACKET_START, CharUtil.BRACKET_END };
private boolean isStartWith$ = false;
protected List patternParts;
/**
* 解析Bean路径表达式为Bean模式
* .表达式，可以获取Bean对象中的属性（字段）值或者Map中key对应的值
* []表达式，可以获取集合等对象中对应index的值
*
*
* 表达式栗子：
*
*
* persion
* persion.name
* persons[3]
* person.friends[5].name
* ['person']['friends'][5]['name']
*
*
* @param expression 表达式
* @return {@link BeanPath}
*/
public static BeanPath create(String expression) {
return new BeanPath(expression);
}
/**
* 构造
*
* @param expression 表达式
*/
public BeanPath(String expression) {
init(expression);
}
/**
* 获取Bean中对应表达式的值
*
* @param bean Bean对象或Map或List等
* @return 值，如果对应值不存在，则返回null
*/
public Object get(Object bean) {
return get(this.patternParts, bean, false);
}
/**
* 设置表达式指定位置（或filed对应）的值
* 1. 如果为List，如果下标不大于List长度，则替换原有值，否则追加值
* 2. 如果为数组，如果下标不大于数组长度，则替换原有值，否则追加值
*
*
* @param bean Bean、Map或List
* @param value 值
*/
public void set(Object bean, Object value) {
set(bean, this.patternParts, value);
}
/**
* 设置表达式指定位置（或filed对应）的值
* 1. 如果为List，如果下标不大于List长度，则替换原有值，否则追加值
* 2. 如果为数组，如果下标不大于数组长度，则替换原有值，否则追加值
*
*
* @param bean Bean、Map或List
* @param patternParts 表达式块列表
* @param value 值
*/
private void set(Object bean, List patternParts, Object value) {
Object subBean = get(patternParts, bean, true);
if(null == subBean) {
set(bean, patternParts.subList(0, patternParts.size() - 1), new HashMap<>());
//set中有可能做过转换，因此此处重新获取bean
subBean = get(patternParts, bean, true);
}
BeanUtil.setFieldValue(subBean, patternParts.get(patternParts.size() - 1), value);
}
// ------------------------------------------------------------------------------------------------------------------------------------- Private method start
/**
* 获取Bean中对应表达式的值
*
* @param patternParts 表达式分段列表
* @param bean Bean对象或Map或List等
* @param ignoreLast 是否忽略最后一个值，忽略最后一个值则用于set，否则用于read
* @return 值，如果对应值不存在，则返回null
*/
private Object get(List patternParts, Object bean, boolean ignoreLast) {
int length = patternParts.size();
if (ignoreLast) {
length--;
}
Object subBean = bean;
boolean isFirst = true;
String patternPart;
for (int i = 0; i < length; i++) {
patternPart = patternParts.get(i);
subBean = getFieldValue(subBean, patternPart);
if (null == subBean) {
// 支持表达式的第一个对象为Bean本身（若用户定义表达式$开头，则不做此操作）
if (isFirst && false == this.isStartWith$ && BeanUtil.isMatchName(bean, patternPart, true)) {
subBean = bean;
isFirst = false;
} else {
return null;
}
}
}
return subBean;
}
@SuppressWarnings("unchecked")
private static Object getFieldValue(Object bean, String expression) {
if (StrUtil.isBlank(expression)) {
return null;
}
if (StrUtil.contains(expression, ':')) {
// [start:end:step] 模式
final List parts = StrUtil.splitTrim(expression, ':');
int start = Integer.parseInt(parts.get(0));
int end = Integer.parseInt(parts.get(1));
int step = 1;
if (3 == parts.size()) {
step = Integer.parseInt(parts.get(2));
}
if (bean instanceof Collection) {
return CollUtil.sub((Collection) bean, start, end, step);
} else if (ArrayUtil.isArray(bean)) {
return ArrayUtil.sub(bean, start, end, step);
}
} else if (StrUtil.contains(expression, ',')) {
// [num0,num1,num2...]模式或者['key0','key1']模式
final List keys = StrUtil.splitTrim(expression, ',');
if (bean instanceof Collection) {
return CollUtil.getAny((Collection) bean, Convert.convert(int[].class, keys));
} else if (ArrayUtil.isArray(bean)) {
return ArrayUtil.getAny(bean, Convert.convert(int[].class, keys));
} else {
final String[] unwrapedKeys = new String[keys.size()];
for (int i = 0; i < unwrapedKeys.length; i++) {
unwrapedKeys[i] = StrUtil.unWrap(keys.get(i), '\'');
}
if (bean instanceof Map) {
// 只支持String为key的Map
MapUtil.getAny((Map) bean, unwrapedKeys);
} else {
final Map map = BeanUtil.beanToMap(bean);
MapUtil.getAny(map, unwrapedKeys);
}
}
} else {
// 数字或普通字符串
return BeanUtil.getFieldValue(bean, expression);
}
return null;
}
/**
* 初始化
*
* @param expression 表达式
*/
private void init(String expression) {
List localPatternParts = new ArrayList<>();
int length = expression.length();
final StrBuilder builder = StrUtil.strBuilder();
char c;
boolean isNumStart = false;// 下标标识符开始
for (int i = 0; i < length; i++) {
c = expression.charAt(i);
if (0 == i && '$' == c) {
// 忽略开头的$符，表示当前对象
isStartWith$ = true;
continue;
}
if (ArrayUtil.contains(expChars, c)) {
// 处理边界符号
if (CharUtil.BRACKET_END == c) {
// 中括号（数字下标）结束
if (false == isNumStart) {
throw new IllegalArgumentException(StrUtil.format("Bad expression '{}':{}, we find ']' but no '[' !", expression, i));
}
isNumStart = false;
// 中括号结束加入下标
if (builder.length() > 0) {
localPatternParts.add(unWrapIfPossible(builder));
}
builder.reset();
} else {
if (isNumStart) {
// 非结束中括号情况下发现起始中括号报错（中括号未关闭）
throw new IllegalArgumentException(StrUtil.format("Bad expression '{}':{}, we find '[' but no ']' !", expression, i));
} else if (CharUtil.BRACKET_START == c) {
// 数字下标开始
isNumStart = true;
}
// 每一个边界符之前的表达式是一个完整的KEY，开始处理KEY
if (builder.length() > 0) {
localPatternParts.add(unWrapIfPossible(builder));
}
builder.reset();
}
} else {
// 非边界符号，追加字符
builder.append(c);
}
}
// 末尾边界符检查
if (isNumStart) {
throw new IllegalArgumentException(StrUtil.format("Bad expression '{}':{}, we find '[' but no ']' !", expression, length - 1));
} else {
if (builder.length() > 0) {
localPatternParts.add(unWrapIfPossible(builder));
}
}
// 不可变List
this.patternParts = Collections.unmodifiableList(localPatternParts);
}
/**
* 对于非表达式去除单引号
*
* @param expression 表达式
* @return 表达式
*/
private static String unWrapIfPossible(CharSequence expression) {
if (StrUtil.containsAny(expression, " = ", " > ", " < ", " like ", ",")) {
return expression.toString();
}
return StrUtil.unWrap(expression, '\'');
}
// ------------------------------------------------------------------------------------------------------------------------------------- Private method end
}
