http断点续传简单实现（java)

/* >P9|?:c  
**SiteFileFetch.java =x xN3Ay  
*/ nF5\iV  
package NetFox; HZawB25{  
import java.io.*; ^)nIf)9}7  
import java.net.*; gmqL,H#  
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public class SiteFileFetch extends Thread { YHp]O+c  
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SiteInfoBean siteInfoBean = null; //文件信息Bean <eh<4_<qF  
long[] nStartPos; //开始位置 gcA,u)z}R  
long[] nEndPos; //结束位置 NiSybyR$  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 uFUVcWt  
long nFileLength; //文件长度 _'mK=`>u  
boolean bFirst = true; //是否第一次取文件 TpGnSD  
boolean bStop = false; //停止标志 Z~3  
File tmpFile; //文件下载的临时信息 vNDf1B5z  
DataOutputStream output; //输出到文件的输出流 FyhLMW3  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 0{'m":D9  
public SiteFileFetch(SiteInfoBean bean) throws IOException 0sP*ChY5S  
{ )i^S:2  
siteInfoBean = bean; Krd0Gc~\|  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); wZg~k\_lF  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 0K(&EpVE  
if(tmpFile.exists ()) pf`vH`r  
{ <{cf'"O7)  
bFirst = false; P_.zp5>  
read_nPos(); *5KDu$'(e  
} B'-n ^';  
else C <d]0)  
{ zi_0*znw  
nStartPos = new long[bean.getNSplitter()]; 0i>>CvAl}  
nEndPos = new long[bean.getNSplitter()]; T(=Z0M  
} sZ>0*S  
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} Aj*|
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public void run() R9-Uoc/  
{ y[';@t7CC  
//获得文件长度 .wPI%5D  
//分割文件 wln"g,ct  
//实例FileSplitterFetch VKcVwq  
//启动FileSplitterFetch线程 mq+x=  
//等待子线程返回 ^g=j`f[T  
try{ YRyaOrl$<  
if(bFirst) ! Q8y]9O  
{ 0*,]`A=  
nFileLength = getFileSize(); z:;yx  
if(nFileLength == -1) ojx2[a\  
{ C$d b)5-  
System.err.println("File Length is not known!"); O jH"qi  
} A"6

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else if(nFileLength == -2) \;1nEjIA  
{ )T@?.J`  
System.err.println("File is not access!"); ?>NX}~2cf  
} J;N\q  
else y$9XHubu  
{ U^kk0OT^  
for(int i=0;i<nStartPos.length;i++) qG3MyK%O\  
{ eMtQa;Lc9o  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); #i=m%>zjN  
} i)(-Ad_  
for(int i=0;i<nEndPos.length-1;i++) HfEl TC:3f  
{ =vsvx{o?  
nEndPos = nStartPos[i+1]; (gUVZeVFP  
} _QneaPm%  
nEndPos[nEndPos.length-1] = nFileLength; q}C;~nMD  
} 23X-h#w  
} A]MX^eY  
^sF(IV[>  
p: u@? k  
//启动子线程 l4YTR4D  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; W^i[7 r  
for(int i=0;i<nStartPos.length;i++) "}b/[U@>  
{ )BZ6QO`5n  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), |=[._VH1  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), }?*$AVs2q  
nStartPos,nEndPos,i); Qp-P[Tc  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 19i=kdH  
fileSplitterFetch.start(); nnTiu,2R  
} SP4(yJy&  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), SmV}Wf  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); y24/lc  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", \)cbg#v  
nEndPos = " + nFileLength); /d>Jkv  
// fileSplitterFetch[nPos.length-1].start(); f.:0T&%G  
n`D-?]*  
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//等待子线程结束 ]Aj5 K  
//int count = 0; "Mh}n-oju  
//是否结束while循环 p+CK+m   
boolean breakWhile = false; Ki(0s  
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while(!bStop) pwl7aC+6d  
{ awSi0*d~  
write_nPos(); 4 ;^  
Utility.sleep(500); SKo*8r   
breakWhile = true; ^ R3g7 DG  
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for(int i=0;i<nStartPos.length;i++) [ub)`-6 u  
{ G#3$sz  
if(!fileSplitterFetch.bDownOver) X\5EF7:S  
{ [@0Hmd7  
breakWhile = false; [pSQ8zdF"  
break; L"}2Y3
 
} ew,g'$drD  
} ZFtN~Tg  
if(breakWhile) 2,p= %  
break; wvH*<,8Vq  
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?  
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//count++; &&Otj-n5  
//if(count>4) }sM_^&e4X  
// siteStop(); O*9d[jw[  
} VVc-Dx  
,PX7}//X^  
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System.err.println("文件下载结束！"); j^ttTq|l  
} hne}G._b  
catch(Exception e){e.printStackTrace ();} JR|P
]}  
} LGWQBEXw  
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//获得文件长度 gh%Q9Ni-  
public long getFileSize() T8Ye+eP}  
{ q]v{o8:U  
int nFileLength = -1; 2'8I/>-  
try{ Sv[+~co<l  
URL url = new URL(siteInfoBean.getSSiteURL()); Obc wmL  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); {mA#'75a#  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2Iq*7n:v0  
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int responseCode=httpConnection.getResponseCode(); '3B7F5uLx"  
if(responseCode>=400) !~]'&9  
{ _J0(GuG=~  
processErrorCode(responseCode); ]"i^VVw  
return -2; //-2 represent access is error #3YYE5cB  
} S>R40T=e  
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String sHeader; >"D0vj  
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for(int i=1;;i++) 8CRwHDB  
{ FZ
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ^Fwdi#g  
//Utility.log(in.readLine()); 8%;]]{(B  
sHeader=httpConnection.getHeaderFieldKey(i); h[gKyxZ/t  
if(sHeader!=null) &usum~@  
{ VB~Do?]*k%  
if(sHeader.equals("Content-Length")) 3MoVIf1  
{ yXro6u?
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); r?WOum  
break; da$ErN'{  
} n;r W  
} 8b $e)  
else uD:tT~  
break; 3EyVoS6D  
} =2d h}8Mz  
} %&iWc_"  
catch(IOException e){e.printStackTrace ();} sB<y(}u  
catch(Exception e){e.printStackTrace ();} CjU?3Ag  
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Utility.log(nFileLength); z?(QM:  
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return nFileLength; fCi1JH;  
} k;vhQ=  
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//保存下载信息（文件指针位置） jn>RE   
private void write_nPos() ./}W3  
{ incUa;  
try{ $e,'<Jl  
output = new DataOutputStream(new FileOutputStream(tmpFile)); yo#fJ`  
output.writeInt(nStartPos.length); +JY]J89  
for(int i=0;i<nStartPos.length;i++) o*s3"Ib  
{ =kn-F T  
// output.writeLong(nPos); r~T3Ieb
 
output.writeLong(fileSplitterFetch.nStartPos); i}Cy q  
output.writeLong(fileSplitterFetch.nEndPos); )5ISkbsxD  
} \rmge4`4  
output.close(); Eo_;Nc  
} CL"q"  
catch(IOException e){e.printStackTrace ();} q@Sj$  
catch(Exception e){e.printStackTrace ();} aTPmW]w6  
} M}`G}*  
s F3M= uz  
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//读取保存的下载信息（文件指针位置） ri1:q.:I]  
private void read_nPos() |BA<> WE  
{ L@8C t  
try{ ftbOvG/ I  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); VseeU;q
 
int nCount = input.readInt(); 5gY9D!;:0D  
nStartPos = new long[nCount]; #nJ&`woZt  
nEndPos = new long[nCount]; y7Y g$)sL  
for(int i=0;i<nStartPos.length;i++) T>pz?e^5&  
{ !<j
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nStartPos = input.readLong(); '1Q [&  
nEndPos = input.readLong(); =bB7$#al  
} 73kL>u  
input.close(); v(z2,?/4  
} &Ch~$Wb^  
catch(IOException e){e.printStackTrace ();} c9R|0Yn^J  
catch(Exception e){e.printStackTrace ();} o|7 h  
} #"aL M6Cfs  
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private void processErrorCode(int nErrorCode) nN!R!tJPa  
{ xsSX~`  
System.err.println("Error Code : " + nErrorCode); ^_pJEX  
} 6*=
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A0 1D-)  
//停止文件下载 wv_<be[?*  
public void siteStop() $+@xwuY'+  
{ UJ6zgsD1b?  
bStop = true; 2q*aq%  
for(int i=0;i<nStartPos.length;i++) };@J)}  
fileSplitterFetch.splitterStop(); IRl(H_.  
+~1~f'4J  
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} #[ch?K  
} {aq}Q|?/  
//负责部分文件的抓取 g\foBK:GE  
**FileSplitterFetch.java sn.&|)?Fi  
*/ "N*i!
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package NetFox; ad[oor/7|  
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import java.io.*; ,Frdi>7 ~  
import java.net.*; )m[dfeqd +  
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public class FileSplitterFetch extends Thread { Bwg\_:vq
 
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String sURL; //File URL w00
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long nStartPos; //File Snippet Start Position *q |3QHZ  
long nEndPos; //File Snippet End Position k?'<f  
int nThreadID; //Thread's ID B[nkE+s  
boolean bDownOver = false; //Downing is over \]+57^8r  
boolean bStop = false; //Stop identical N(BCe\FV  
FileAccessI fileAccessI = null; //File Access interface
#Ez+1  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ,7nA:0P  
{ Vm <9/UG<  
this.sURL = sURL; uw`fC%-xh  
this.nStartPos = nStart; 26<Wg7/,  
this.nEndPos = nEnd; W;@9x1jKX  
nThreadID = id; ,=Fn6'  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 yCG<qQz  
} @%sr#YqY  
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|=W=H6h*  
public void run() hCKx%&[^7  
{ JOm6Zc  
while(nStartPos < nEndPos && !bStop) J=C63YB  
{ R x.]m0  
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try{ OGq
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URL url = new URL(sURL); ,%%}d9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); fK{[=xMr@  
httpConnection.setRequestProperty("User-Agent","NetFox"); JDy;Jb  
String sProperty = "bytes="+nStartPos+"-"; I~.d/!
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httpConnection.setRequestProperty("RANGE",sProperty); <OC|z3na_  
Utility.log(sProperty); .&Ok53]b  

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InputStream input = httpConnection.getInputStream(); ^HasT4M+x  
//logResponseHead(httpConnection); auS.q5 %  
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byte[] b = new byte[1024]; r(::3TF%#q  
int nRead; --9Z  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Nu%:7  
{ hfuGCD6F`  
nStartPos += fileAccessI.write(b,0,nRead); 'N?t=A  
//if(nThreadID == 1) 3@7<e~f  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -d8||X[  
} t[-0/-4  
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}.R].4gT  
Utility.log("Thread " + nThreadID + " is over!"); (&a<6k  
bDownOver = true; WgK|r
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//nPos = fileAccessI.write (b,0,nRead); QP?Deltp  
} $=-Q]ld&]  
catch(Exception e){e.printStackTrace ();} ']]&<B}mz  
} GXE6=B
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} @\UoZv(  
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//打印回应的头信息 5h4E>LB.B  
public void logResponseHead(HttpURLConnection con) %Fg}"=f1  
{ g}]EIv{  
for(int i=1;;i++) XN=Cq*3}  
{ 66+y@l1  
String header=con.getHeaderFieldKey(i); t9Nu4yl  
if(header!=null) *(4TasQu  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Y/1,%8n  
Utility.log(header+" : "+con.getHeaderField(header)); o-D,K dY  
else Iu -CXc  
break; AIXvS*Y,  
} WZ<kk T  
} OLdD3OI  
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public void splitterStop() %$l^C!qcY  
{ -Jt
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bStop = true; 6^DsI  
} ;I+"MY7D  
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} {&Bpf K;`)  
;\$P;-VY  
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/* Yv`8{
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**FileAccess.java
vsM] <t  
*//文件访问(定位，写) Gkr^uXNg#  
package NetFox; v0dFP0.;&  
import java.io.*; 2z\4?HJy  
$VrKoL\ScA  
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public class FileAccessI implements Serializable{ #NVqS5  
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h  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Hhbf9)  
RandomAccessFile oSavedFile; ikGH:{  
long nPos; yMNLsR~rh  
LxGE<xj|V%  
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public FileAccessI() throws IOException l}DCK  
{ IKK<D'6  
this("",0); K+` Vn  
} :);]E-ch  
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public FileAccessI(String sName,long nPos) throws IOException toipEp<ci  
{ !j(KbAhWZ  
oSavedFile = new RandomAccessFile(sName,"rw"); MGO.dRy_  
this.nPos = nPos; 9rb/hkX&  
oSavedFile.seek(nPos); [hg|bpEG  
} K;f'&9-+i,  
4M8AYh2)  
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public synchronized int write(byte[] b,int nStart,int nLen) |7Q8WjCQ{m  
{ R0<ka[+  
int n = -1; n;"4`6L~  
try{ z#!xqIg0  
oSavedFile.write(b,nStart,nLen); 7[-jr;v  
n = nLen; sQ^>.yG  
} Y\T*8\h_[  
catch(IOException e) rI}E2J  
{ ~zz
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e.printStackTrace (); ru`;cXa,  
} T^a {#B  
13
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return n; W4CI=94  
} $/C<^}A  
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} h6x+.}}  
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/* 7/vr!tbL`p  
**SiteInfoBean.java U!a"r8u|8q  
*/ +29;T0>a  
package NetFox; T , =ga  
P&aH6*p1  
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public class SiteInfoBean { 3i(k6)H$4  
MatC2-aV1  
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private String sSiteURL; //Site's URL (?\ZN+V)  
private String sFilePath; //Saved File's Path gE=~.P[Z
X  
private String sFileName; //Saved File's Name )C2d)(baEJ  
private int nSplitter; //Count of Splited Downloading File 1|w,Z+/  
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public SiteInfoBean() LO61J_J<  
{//nSplitter的缺省值为5 YLd 5  
//default value of nSplitter is 5 d L%
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this("","","",5); o33{tUp'  
} +lha^){  
l3MbCBX2  
8 (^2  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) >KY\Bx  
{ >q &ouVE  
sSiteURL= sURL; *A\NjXJl~  
sFilePath = sPath; SA>;]6)`(  
sFileName = sName; .%wEuqW=0  
this.nSplitter = nSpiltter; )Qxv9:X  
p>eD{#2  
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} @?]-5~3;  
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public String getSSiteURL() Sw1]]-Es  
{ N~>?w#?J  
return sSiteURL; CJKH"'u3^  
} Z `\7B e  
^}1RDdQ"U  
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public void setSSiteURL(String value) RO.(k!J .  
{ vWkKNB  
sSiteURL = value; "(efd~.]  
} x#8=drh.:C  
,t+ATaOF  
r3j8[&B"  
public String getSFilePath() Zc4hjg  
{ "}HQ)54&  
return sFilePath; _Mt:^H}Sy  
} _TPo=}Z  
<Ab:yD`K!  
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public void setSFilePath(String value) mTP.W#N
 
{ BWPYHWW}E  
sFilePath = value; (x^|  
} "tj#P  
17i^|&J6}:  

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public String getSFileName() F{"%ey">  
{ m~U{ V9;*  
return sFileName; ;ZqFrHI M`  
} .FXQ,7mZ-  
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public void setSFileName(String value) Q~@8t"P  
{ O^xt  
sFileName = value; .-|O"H$  
} rka:.#!  
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"|G,P-5G"  
public int getNSplitter() IB6]Wj  
{ k`AJ$\=  
return nSplitter; K?tk&0  
} PW`Tuj  
,pASjFWi  
``<1Lo@  
public void setNSplitter(int nCount) S }n;..{  
{ 2bJFlxEU  
nSplitter = nCount; <di_2hN  
} 2$o[  
}
F
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}gW}Vr <  
/* l17ZNDzLU  
**Utility.java LNZ#%R~r  
*/ itF+6wv~  
package NetFox; _5T7A><q<  
^8
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@,MdvR+a  
public class Utility { /(V=Um^0  
>&&xJ5  
UYQ$c }Z5  
public Utility() Pp/{
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{ !-c*lb  
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} ~{+{pcO}  
h2%:;phH  
//线程睡眠 >>$|,Q-.  
public static void sleep(int nSecond) !T*B{+|  
{ V)2_T!e%*  
try{ A,{D9-%  
Thread.sleep(nSecond); $)3PF  
} doc  
catch(Exception e) 6EU4  
{ ?i~/gjp  
e.printStackTrace (); pCmJY  
} u =kSs  
} 3@] a#>  
@(c<av?  
//日志 -YV4  O  
public static void log(String sMsg) ? ~
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{ $-]setdY  
System.err.println(sMsg); ^,K.)s  
} 

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?
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0lCd,a2:  
public static void log(int sMsg) RuNH (>Eb  
{ ennz/'  
System.err.println(sMsg); " B{0-H+  
} 1ckw[0d  
} &t/<yq}{  
kA<r:/  
?ev G=S4>  
/* .p9h$z^  
**TestMethod.java P$/A!r  
*/ /Q8A"'Nk  
package NetFox; 1K9?a;.  
[|n-x3h  
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public class TestMethod { d:pm|C|F  
%`T5a<   
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public TestMethod() 6Y)^)dOi  
{ ///xx/weblogic60b2_win.exe !*Z)[[  
try{ e K1m(E.=  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); j' KobyX<  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); K4/P(*r`  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 0^.4eX:E_  
fileFetch.start(); ~_db<!a  
} P .4b+9Tx  
catch(Exception e){e.printStackTrace ();} L*01l"
5  
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$a*Q).^  
} c9TAV,/fF*  
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*7;*@H*jd  
public static void main(String[] args) Cn;H@!8<s  
{ SE9u2Jk  
new TestMethod(); qm8n7Z/  
} C.)&FW2F_  
} Bb[e[,ah  
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