java - Spring 3 对象与原始数据类型的绑定(bind)列表

Question

我是初学者，正在使用 Spring 3。

我有以下 bean

public class Record {
    private String title;
    private double amount;

    //Getter and Setter
}

public class RecordBean {
    private List<Record> records;

    public RecordBean() {
        this.records = LazyList.lazyList(new ArrayList<Record>(), new InstantiateFactory<Record>(Record.class));
    }

    //Getter and Setter
}

我已添加RecordBean至model

modelMap.add('recordBean',new RecordBean());

以下是 Spring 形式

<form:form action="/save" method="POST" commandName="recordBean">

    <form:input path="records[0].title"/>
    <form:input path="records[0].amount"/>

    <form:input path="records[1].title"/>
    <form:input path="records[1].amount"/>

    <input type="submit" value="Save"/>
</form:form>

我还添加了InitBinder到 Controller

@InitBinder
public void initBinder(WebDataBinder binder) {
    binder.registerCustomEditor(Double.class, new CustomNumberEditor(Double.class, true));
}

现在，如果我输入 amount[0] 的值并将 amount[1] 留空并提交表格，我得到 typeMismatch错误。

Field error in object 'recordBean' on field 'records[1].amount': rejected value []; codes [typeMismatch.recordBean.records[1].amount,typeMismatch.recordBean.records.amount,typeMismatch.records[1].amount,typeMismatch.records.amount,typeMismatch.amount,typeMismatch.double,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [recordBean.records[1].amount,records[1].amount]; arguments []; default message [records[1].amount]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'double' for property 'records[1].amount'; nested exception is java.lang.NumberFormatException: empty String]

请指教。

谢谢

Answer 1

也许尝试将这一行从“double”更改为“Double”:

private double amount;