EJBQL 中 Seam 限制的使用
我对 Seam 很陌生，我需要在下面的代码中进行一些澄清，我需要知道它是如何工作的，在这段代码中 RESTRICTIONS 有什么用......
package org.domain.pixel.action;
import org.domain.pixel.entity.*;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.framework.EntityQuery;
import java.util.Arrays;
@Name("projectList")
public class ProjectList extends EntityQuery<Project> {
private static final long serialVersionUID = -7673337640345325071L;
private static final String EJBQL = "select project from Project project";
private static final String[] RESTRICTIONS = {
"lower(project.processOwner) like lower(concat(#{projectList.project.processOwner},'%'))",
"lower(project.projectName) like lower(concat(#{projectList.project.projectName},'%'))",
};
private Project project = new Project();
public ProjectList() {
;
setEjbql(EJBQL);
setRestrictionExpressionStrings(Arrays.asList(RESTRICTIONS));
setMaxResults(25);
}
public Project getProject() {
return project;
}
}
I am very new to Seam, I need some clarification in this below code , I need to know how it works, what is use of RESTRICTIONS in this code .......
package org.domain.pixel.action;
import org.domain.pixel.entity.*;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.framework.EntityQuery;
import java.util.Arrays;
@Name("projectList")
public class ProjectList extends EntityQuery<Project> {
private static final long serialVersionUID = -7673337640345325071L;
private static final String EJBQL = "select project from Project project";
private static final String[] RESTRICTIONS = {
"lower(project.processOwner) like lower(concat(#{projectList.project.processOwner},'%'))",
"lower(project.projectName) like lower(concat(#{projectList.project.projectName},'%'))",
};
private Project project = new Project();
public ProjectList() {
;
setEjbql(EJBQL);
setRestrictionExpressionStrings(Arrays.asList(RESTRICTIONS));
setMaxResults(25);
}
public Project getProject() {
return project;
}
}
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评论（1）
您发布的代码是Seam 中为基于列表的视图创建支持bean（或“操作”）的标准方法。
ProjectList基于 JPA 查询（称为“EJBQL”）创建一个结果集，并且限制是为此查询动态创建 WHERE 子句的一种方法，例如基于用户输入。用户输入很可能放置在名为“
project”的实例变量中。限制（总共 2 个）仅选择processOwner和projectName等于processOwner 的记录（来自与 Project 实体类对应的表）以及“project”中设置的projectName（基于不区分大小写的比较）。The code you posted is a standard approach in Seam to create a backing bean (or "action") for views that are list-based. The
ProjectListcreates a result set based on the JPA query (called "EJBQL"), and the restrictions are a a means to dynamically create a WHERE clause for this query, for instance based on user input.The user input is most likely placed in the instance var called "
project". The restrictions (2 in total) select only records (from the table corresponding to the Project entity class) for which theprocessOwnerAND theprojectNameare equal to theprocessOwnerAND theprojectNameset in "project" (based on a case-insensitive comparison).