解释这段代码List<String> collect = queue.stream().filter(item -> programList.contains(item)).collect(Collectors.toList());
时间: 2024-05-28 19:13:38 浏览: 22
这段代码使用 Java 8 的 Stream API 对一个 List 进行过滤操作,返回符合条件的元素集合。
具体来说,假设有一个名为 queue 的 List<String> 对象,还有一个名为 programList 的 List<String> 对象,那么这段代码就会过滤出 queue 中包含在 programList 中的元素,将它们放到一个新的 List<String> 中,并把这个新的 List 返回给 collect 变量。
其中,filter() 方法用于过滤元素,接受一个 Lambda 表达式作为参数。这个 Lambda 表达式用于判断元素是否符合条件,如果符合,就返回 true,否则返回 false。在这个例子中,Lambda 表达式为 item -> programList.contains(item),表示当 item 在 programList 中时,返回 true,否则返回 false。
collect() 方法用于将过滤后的元素收集成一个新的集合。在这个例子中,使用 toList() 方法将过滤后的元素收集成一个 List<String> 对象。
相关问题
List<SchemaRowRule> userRowRuleList = schemaRowRuleList.stream() .filter(schemaRowRuleEo -> { List<String> userList = JSONArray.parseArray(schemaRowRuleEo.getRowPermissionUserList(), String.class); List<String> orgList = JSONArray.parseArray(schemaRowRuleEo.getRowPermissionOrgList(), String.class); return userList.contains(userUid) || orgList.contains(orgCode); }) .map(schemaRowRuleEo -> { SchemaRowRule schemaRowRule = SchemaRowRule.builder().build(); BeanUtils.copyProperties(schemaRowRuleEo, schemaRowRule); return schemaRowRule; }) .collect(Collectors.toList()); List<SchemaColumnRule> userColumnRuleList = schemaColumnRuleList.stream() .filter(rule -> { if (StringUtils.isNotEmpty(rule.getColumnPermissionUserList())) { List<String> userList = JSONArray.parseArray(rule.getColumnPermissionUserList(), String.class); return userList.contains(userUid); } else if (StringUtils.isNotEmpty(rule.getColumnPermissionOrgList())) { List<String> orgList = JSONArray.parseArray(rule.getColumnPermissionOrgList(), String.class); return orgList.contains(orgCode); } return false; }) .map(rule -> { SchemaColumnRule columnRule = new SchemaColumnRule(); BeanUtils.copyProperties(rule, columnRule); return columnRule; }) .collect(Collectors.toList());优化代码
可以考虑使用方法引用来简化Lambda表达式,同时避免多次解析JSON字符串,代码如下:
```
List<SchemaRowRule> userRowRuleList = schemaRowRuleList.stream()
.filter(schemaRowRuleEo -> {
List<String> userList = JSONArray.parseArray(schemaRowRuleEo.getRowPermissionUserList(), String.class);
List<String> orgList = JSONArray.parseArray(schemaRowRuleEo.getRowPermissionOrgList(), String.class);
return userList.contains(userUid) || orgList.contains(orgCode);
})
.map(schemaRowRuleEo -> {
SchemaRowRule schemaRowRule = new SchemaRowRule();
BeanUtils.copyProperties(schemaRowRuleEo, schemaRowRule);
return schemaRowRule;
})
.collect(Collectors.toList());
List<SchemaColumnRule> userColumnRuleList = schemaColumnRuleList.stream()
.filter(rule -> {
List<String> userList = Optional.ofNullable(rule.getColumnPermissionUserList())
.map(jsonArray -> JSONArray.parseArray(jsonArray, String.class))
.orElse(Collections.emptyList());
List<String> orgList = Optional.ofNullable(rule.getColumnPermissionOrgList())
.map(jsonArray -> JSONArray.parseArray(jsonArray, String.class))
.orElse(Collections.emptyList());
return userList.contains(userUid) || orgList.contains(orgCode);
})
.map(BeanUtils::instantiate)
.collect(Collectors.toList());
```
其中,使用了`Optional`来避免`null`值的判断和处理,使用`BeanUtils::instantiate`方法引用来创建对象并复制属性。
List<DataPermissionSchemaEo> dataPermissionSchemaEoList = comDataComponent.getDataPermissionSchemaList(); List<SchemaRowRuleEo> schemaRowRuleList = comDataComponent.getSchemaRowRuleList(); List<SchemaColumnRuleEo> schemaColumnRuleList = comDataComponent.getSchemaColumnRuleList(); //设置行权限 根据用户id和用户组织去获取 List<SchemaRowRule> userRowRuleList = schemaRowRuleList.stream() .filter(schemaRowRuleEo -> { List<String> userList = JSONObject.parseArray(schemaRowRuleEo.getRowPermissionUserList(), String.class); List<String> orgList = JSONObject.parseArray(schemaRowRuleEo.getRowPermissionOrgList(), String.class); return userList.contains(userUid) || orgList.contains(orgCode) || userList.contains(WILDCARD) || orgList.contains(WILDCARD); }) .map(schemaRowRuleEo -> { SchemaRowRule schemaRowRule = new SchemaRowRule(); BeanUtils.copyProperties(schemaRowRuleEo, schemaRowRule); return schemaRowRule; }) .collect(Collectors.toList());List<SchemaColumnRule> userColumnRuleList = schemaColumnRuleList.stream() .filter(rule -> { List<String> userList = Optional.ofNullable(rule.getColumnPermissionUserList()) .map(userListStr -> JSONObject.parseArray(userListStr, String.class)) .orElse(Collections.emptyList()); List<String> orgList = Optional.ofNullable(rule.getColumnPermissionOrgList()) .map(orgListStr -> JSONObject.parseArray(orgListStr, String.class)) .orElse(Collections.emptyList()); return userList.contains(userUid) || orgList.contains(orgCode) || userList.contains(WILDCARD) || orgList.contains(WILDCARD); }) .map(rule -> { SchemaColumnRule columnRule = new SchemaColumnRule(); BeanUtils.copyProperties(rule, columnRule); return columnRule; }) .collect(Collectors.toList()); List<DataPermissionSchema> dataPermissionSchemaList = dataPermissionSchemaEoList.stream().map(dataPermissionSchemaEo -> { List<SchemaRowRule> schemaRowRules = userRowRuleList.stream() .filter(schemaRule -> dataPermissionSchemaEo.getDatabaseCode().equals(schemaRule.getDatabaseCode()) && dataPermissionSchemaEo.getSchemaCode().equals(schemaRule.getSchemaCode())) .collect(Collectors.toList()); List<SchemaColumnRule> schemaColumnRules = userColumnRuleList.stream() .filter(schemaRule -> dataPermissionSchemaEo.getDatabaseCode().equals(schemaRule.getDatabaseCode()) && dataPermissionSchemaEo.getSchemaCode().equals(schemaRule.getSchemaCode())) .collect(Collectors.toList()); if(!schemaRowRules.isEmpty() || !schemaColumnRules.isEmpty()) { DataPermissionSchema dataPermissionSchema = new DataPermissionSchema(); dataPermissionSchema.setDatabaseCode(dataPermissionSchemaEo.getDatabaseCode()); dataPermissionSchema.setSchemaCode(dataPermissionSchemaEo.getSchemaCode()); dataPermissionSchema.setSchemaRowRuleList(schemaRowRules); dataPermissionSchema.setSchemaColumnRuleList(schemaColumnRules); return dataPermissionSchema; } return null; }).filter(Objects::nonNull).collect(Collectors.toList());把这段代码改造成每个用户拥有的行权限和列权限
可以将该代码封装成一个方法,接收用户ID和组织代码作为参数,返回该用户拥有的行权限和列权限,代码如下:
```
public List<DataPermissionSchema> getUserDataPermissionSchema(String userUid, String orgCode) {
List<DataPermissionSchemaEo> dataPermissionSchemaEoList = comDataComponent.getDataPermissionSchemaList();
List<SchemaRowRuleEo> schemaRowRuleList = comDataComponent.getSchemaRowRuleList();
List<SchemaColumnRuleEo> schemaColumnRuleList = comDataComponent.getSchemaColumnRuleList();
// 获取用户行权限
List<SchemaRowRule> userRowRuleList = schemaRowRuleList.stream()
.filter(schemaRowRuleEo -> {
List<String> userList = JSONObject.parseArray(schemaRowRuleEo.getRowPermissionUserList(), String.class);
List<String> orgList = JSONObject.parseArray(schemaRowRuleEo.getRowPermissionOrgList(), String.class);
return userList.contains(userUid) || orgList.contains(orgCode) || userList.contains(WILDCARD) || orgList.contains(WILDCARD);
})
.map(schemaRowRuleEo -> {
SchemaRowRule schemaRowRule = new SchemaRowRule();
BeanUtils.copyProperties(schemaRowRuleEo, schemaRowRule);
return schemaRowRule;
})
.collect(Collectors.toList());
// 获取用户列权限
List<SchemaColumnRule> userColumnRuleList = schemaColumnRuleList.stream()
.filter(rule -> {
List<String> userList = Optional.ofNullable(rule.getColumnPermissionUserList())
.map(userListStr -> JSONObject.parseArray(userListStr, String.class))
.orElse(Collections.emptyList());
List<String> orgList = Optional.ofNullable(rule.getColumnPermissionOrgList())
.map(orgListStr -> JSONObject.parseArray(orgListStr, String.class))
.orElse(Collections.emptyList());
return userList.contains(userUid) || orgList.contains(orgCode) || userList.contains(WILDCARD) || orgList.contains(WILDCARD);
})
.map(rule -> {
SchemaColumnRule columnRule = new SchemaColumnRule();
BeanUtils.copyProperties(rule, columnRule);
return columnRule;
})
.collect(Collectors.toList());
// 获取用户权限所在的数据权限模板
List<DataPermissionSchema> dataPermissionSchemaList = dataPermissionSchemaEoList.stream().map(dataPermissionSchemaEo -> {
List<SchemaRowRule> schemaRowRules = userRowRuleList.stream()
.filter(schemaRule -> dataPermissionSchemaEo.getDatabaseCode().equals(schemaRule.getDatabaseCode())
&& dataPermissionSchemaEo.getSchemaCode().equals(schemaRule.getSchemaCode()))
.collect(Collectors.toList());
List<SchemaColumnRule> schemaColumnRules = userColumnRuleList.stream()
.filter(schemaRule -> dataPermissionSchemaEo.getDatabaseCode().equals(schemaRule.getDatabaseCode())
&& dataPermissionSchemaEo.getSchemaCode().equals(schemaRule.getSchemaCode()))
.collect(Collectors.toList());
if(!schemaRowRules.isEmpty() || !schemaColumnRules.isEmpty()) {
DataPermissionSchema dataPermissionSchema = new DataPermissionSchema();
dataPermissionSchema.setDatabaseCode(dataPermissionSchemaEo.getDatabaseCode());
dataPermissionSchema.setSchemaCode(dataPermissionSchemaEo.getSchemaCode());
dataPermissionSchema.setSchemaRowRuleList(schemaRowRules);
dataPermissionSchema.setSchemaColumnRuleList(schemaColumnRules);
return dataPermissionSchema;
}
return null;
}).filter(Objects::nonNull).collect(Collectors.toList());
return dataPermissionSchemaList;
}
```
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