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我有这个Expeption，不知道如何解决它......

我有一个布尔列表女巫，我想填写一个 JSP，复选框的名称在另一个字符串列表中，如果列表中有 3 个字符串，则应该有 3 个复选框，如果是 4 个字符串，则为 4 个，依此类推

这是我的 JSP

<form:form action="/SpringMVC/dbChanges/form" commandName="index" method="POST">
    <div>
        <h2>neu anlegen:</h2>
        <table>
            <tr><td>Name:&nbsp;<form:input path="name" style="float: right"/></td><td><div class="errors"><form:errors path="name"/></div></td></tr>
            <tr><td>Datum:&nbsp;<form:input path="date" style="float: right"/></td><td><div class="errors"><form:errors path="date"/></div></td></tr>
            <tr><td>Nummer:&nbsp;<form:input path="number" style="float: right"/></td><td><div class="errors"><form:errors path="number"/></div></td></tr>
            <c:forEach var="systemListEntry" items="${systemList}" varStatus="status">
                <tr><td>${systemListEntry.name}: <form:checkbox path="system[${status.index}]" style="float: right"/></td></tr>
            </c:forEach>
        </table>
        <input type="submit" value="Speichern" />
    </div>
</form:form>

这是我的控制器中的方法：

@Controller
@RequestMapping("/dbChanges")
@SessionAttributes("changes")
public class DbChangesControllerImpl implements DbChangeController {

private DbChangeService dbChangeService;
private DbChangeValidator validator;

@Autowired
public DbChangesControllerImpl(final DbChangeValidator pValidator,
        final DbChangeService pDbChangeService) {
    validator = pValidator;
    dbChangeService = pDbChangeService;
}

// Changes //

@Override
@RequestMapping(value = "index.html", method = RequestMethod.GET)
public ModelAndView getChanges() {

    final List<DbChange> list = dbChangeService.getDbEntrys();

    final ModelAndView model = new ModelAndView("index", "index",
            new DbChange());
    model.addObject("dbChanges", list);
    model.addObject("systemList", dbChangeService.getSystems());

    model.addObject("year",
            java.util.Calendar.getInstance().get(java.util.Calendar.YEAR));

    return model;
}
...

dbChangeService.getSystems() 返回一个 FdcSystems 列表：

public class FdcSystem {
private String oid;
private String name;

public String getName() {
    return name;
}

public void setName(final String pName) {
    name = pName;
}

public String getOid() {
    return oid;
}
}

和我绑定到“索引”的 dbChange 对象在这里：

package com.bla.dbchanges;

import java.util.ArrayList;
import java.util.List;

/**
 *
 * @author Fabio Stuber
 *
 */
// TODO: Impl machen
public class DbChange {
private String name;
private String date;
private int number;
private List<Boolean> systems;

private String oid;

/**
 * Konstruktor ohne Id für die Tests
 */
public DbChange(final String pName, final String pDate, final int pNumber) {
    name = pName;
    date = pDate;
    number = pNumber;
}

public DbChange(final String pOid, final String pName, final String pDate, final int pNumber) {
    oid = pOid;
    name = pName;
    date = pDate;
    number = pNumber;
}

/**
 * default Konstruktor, vom JSP benötigt
 */
public DbChange() {
    systems = new ArrayList<Boolean>();
}

public String getName() {
    return name;
}

public void setName(final String pName) {
    name = pName;
}

public String getDate() {
    return date;
}

public void setDate(final String pDate) {
    date = pDate;
}

public int getNumber() {
    return number;
}

public void setNumber(final int pNumber) {
    number = pNumber;
}

public String getOid() {
    return oid;
}

public void setOid(final String pOid) {
    oid = pOid;
}

public List<Boolean> getSystems() {
    return systems;
}

public void setSystems(final List<Boolean> pSystems) {
    systems = pSystems;
}

public void addSystem(final Boolean system) {
    systems.add(system);
}

}

dbChangesServiceImpl

package com.bla.dbchanges;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.springframework.beans.factory.annotation.Autowired;

import com.bla.dbchanges.context.DbChangeFactory;
import com.bla.dbchanges.model.FdcDbchange;
import com.bla.dbchanges.model.FdcSystem;

public class DbChangeServiceImpl implements DbChangeService {
private final DbChangeDataStoreManager manager;
private final DbChangeFactory factory;

@Autowired
public DbChangeServiceImpl(final DbChangeDataStoreManager pNewManager,
        final DbChangeFactory pFactory) {
    manager = pNewManager;
    factory = pFactory;
}

private Date convertStringToDate(final String date) {
    Date parsedDate = new Date();

    try {
        parsedDate = new SimpleDateFormat("dd.MM.yyyy").parse(date);
    } catch (final ParseException e) {
        e.printStackTrace();
    }

    return parsedDate;
}

@Override
public List<DbChange> getDbEntrys() {
    final List<DbChange> list = new ArrayList<DbChange>();

    for (final FdcDbchange fdcChange : manager.getAllChanges()) {
        list.add(factory.createDbChange(fdcChange));
    }

    return list;
}

@Override
public DbChange getSingleChange(final String pOid) {
    final FdcDbchange change = manager.getSingleChange(pOid);

    return factory.createDbChange(change);
}

// TODO: Error, er will statt auf meinen schon vorhandenen Eintrag
// zuzugreiffen, einen neuen erstellen mit der gleichen OID
@Override
public void saveChange(final DbChange pChange) {
    final FdcDbchange change = factory.createFdcDbchange();
    final Set<FdcSystem> systems = new HashSet<FdcSystem>();
    final List<FdcSystem> allSystems = manager.getAllSystems();

    // TODO: evtl Chain sobald error gefixt ist
    if (pChange.getTwa()) {
        systems.add(allSystems.get(0));
    }
    if (pChange.getIwa()) {
        systems.add(allSystems.get(1));
    }
    if (pChange.getPwa()) {
        systems.add(allSystems.get(2));
    }

    change.setChangeDate(convertStringToDate(pChange.getDate()));
    change.setChangeName(pChange.getName());
    change.setChangeNumber(pChange.getNumber());
    change.setSystems(systems);

    manager.saveChange(change);
}

@Override
public void delete(final String pOid) {
    final FdcDbchange changeToDelete = manager.getSingleChange(pOid);

    manager.deleteChange(changeToDelete);
}

@Override
public void editChange(final DbChange pNewChange) {
    final FdcDbchange changeToEdit = manager.getSingleChange(pNewChange
            .getOid());
    final List<FdcSystem> allSystems = manager.getAllSystems();
    final Set<FdcSystem> systems = new HashSet<FdcSystem>();

    // TODO: hier die selbe Chain
    if (pNewChange.getTwa()) {
        systems.add(allSystems.get(0));
    }
    if (pNewChange.getIwa()) {
        systems.add(allSystems.get(1));
    }
    if (pNewChange.getPwa()) {
        systems.add(allSystems.get(2));
    }

    changeToEdit.setSystems(systems);

    manager.editChange(changeToEdit);
}

@Override
public List<FdcSystem> getSystems() {
    final List<String> systems = new ArrayList<String>();
    // for (final FdcSystem system : manager.getAllSystems()) {
    // systems.add(system.getName());
    // }

    return manager.getAllSystems();
}

}

最后，我的例外：

SCHWERWIEGEND：bean 类 [com.bla.dbchanges.DbChange] 的无效属性 'systems[0]'：非法尝试获取属性 'systems' 引发异常；嵌套异常是 org.springframework.beans.NullValueInNestedPathException：bean 类 [com.bla.dbchanges.DbChange] 的无效属性“系统”：无法将属性类型 [java.lang.Boolean] 实例化为自动增长嵌套属性路径：java .lang.InstantiationException：java.lang.Boolean org.springframework.beans.InvalidPropertyException：bean 类 [com.bla.dbchanges.DbChange] 的无效属性 'systems[0]'：非法尝试获取属性 'systems' 引发异常；嵌套异常是 org.springframework.beans.NullValueInNestedPathException：bean 类 [com.bla.dbchanges.DbChange] 的无效属性“系统”：

谁能帮我解决这个问题？

4

2 回答 2

0

您的代码中有错字。

位置

${system.name}: <form:checkbox path="systems[${status.index}]" style="float: right"/>

符合

${system.name}: <form:checkbox path="system[${status.index}]" style="float: right"/>

由于变量名是system而不是systems

于 2015-06-01T13:06:12.600 回答
0

找到了解决方案，将 List 更改为 DbChanges.java 中的 Set：

private Set<String> systems;

并将 JSP 更改为：

<c:forEach var="systemListEntry" items="${systemList}">
    <tr><td>${systemListEntry.name}: <form:checkbox path="systems" value="${systemListEntry.name}" style="float: right"/></td></tr>
</c:forEach>
于 2015-06-01T15:00:17.700 回答